Model 1835-C - Newport Corporation

Model 1835-C 

Multi-Function 

Optical Meter 

OPERATOR’S 

MANUAL


Multi-Function Optical Meter

Warranty 

Newport Corporation warrants this product to be free from defects in material 

and workmanship for a period of 1 year from the date of shipment. If found to 

be defective during the warranty period, the product will either be repaired or 

replaced at Newport’s option. 

To exercise this warranty, write or call your local Newport representative, or 

contact Newport headquarters in Irvine, California. You will be given prompt 

assistance and return instructions. Send the instrument, transportation 

prepaid, to the indicated service facility. Repairs will be made and the instrument 

returned, transportation prepaid. Repaired products are warranted for 

the balance of the original warranty period, or at least 90 days. 

Limitation of Warranty 

This warranty does not apply to defects resulting from modification or misuse 

of any product or part. This warranty also does not apply to fuses, batteries, 

or damage from battery leakage. 

This warranty is in lieu of all other warranties, expressed or implied, including 

any implied warranty of merchantability or fitness for a particular use. 

Newport Corporation shall not be liable for any indirect, special, or 

consequential damages. 

Statement of Calibration 

This instrument has been inspected and tested in accordance with specifications 

published by Newport Corporation. 

The accuracy and calibration of this instrument and photodetector (where 

applicable) is traceable to the National Institute for Standards and Technology 

through equipment which is calibrated at planned intervals by comparison to 

the certified standards maintained at Newport Corporation. 

Copyright 1993, Newport Corporation 

Part No. 20061-01, Rev. D 

IN-05931 (02-00) 

ii

EC DECLARATION OF CONFORMITY 


We declare that the accompanying product, identified with the 

" " mark, meets the intent of the Electromagnetic Compatability 

Directive, 89/336/EEC and Low Voltage Directive 73/23/EEC. 

Compliance was demonstrated to the following specifications: 

EN50081-1 EMISSIONS: 

Radiated and conducted emissions per EN55011, Group 1, 

Class A 

EN50082-1 IMMUNITY: 

Electrostatic Discharge per IEC 1000-4-2, severity level 3 

Radiated Emission Immunity per IEC 1000-4-3, severity level 2 

Fast Burst Transients per IEC 1000-4-4, severity level 3 

Surge Immunity per IEC 1000 4-5, severity level 3 

IEC SAFETY: 

Safety requirements for electrical equipment specified in 

IEC 1010-1. 

Alain Danielo 

Jeff Cannon 

VP European Operations 

General Manager-Precision Systems 

Zone Industrielle 

1791 Deere Avenue 

45340 Beaune-la-Rolande, France Irvine, Ca. USA 

iii

Table of Contents 

Warranty ................................................................................................................. ii 

EC Declaration of Conformity ............................................................................... iii 

List of Figures ........................................................................................................ vii 

List of Tables ........................................................................................................ viii 

Safety Symbols and Terms .................................................................................... ix 

Definitions ............................................................................................................... x 

Specifications ......................................................................................................... xi 

Section 1 – General Information 

1.1 System Overview ...................................................................................... 1 

1.2 Scope of this manual ................................................................................ 2 

1.3 Unpacking and Inspection ........................................................................ 2 

1.4 Preparation for Use .................................................................................. 2 

1.5 Optional Accessories and Services ......................................................... 2 

Section 2 – System Operation 

2.1 Introduction .............................................................................................. 3 

2.2 Display ....................................................................................................... 3 

2.3 Top Level Key Functions .......................................................................... 5 

O I 

2.3.1 , Power .................................................................................... 6 

2.3.2 SHIFT.............................................................................................. 6 

2.3.3 DISP , Display Brightness .......................................................... 6 

2.3.4 FILTER, Signal Filtering ................................................................. 6 

2.3.5 ZERO, Offset Subtraction ............................................................. 7 

2.3.6 AUTO, Automatic Gain Ranging................................................... 7 

2.3.7 STO REF, Store Reference Value .................................................. 7 

2.3.8 ATTN, Attenuator ......................................................................... 8 

2.3.9 λ, Wavelength................................................................................ 8 

2.3.10 RANGE, Signal Range .................................................................... 8 

2.3.11 R/S, Run-Stop................................................................................. 8 

2.3.12 MODE, Measurement Mode ......................................................... 9 

2.3.13 UNITS, Display Units ................................................................... 10 

2.3.14 STATS, Moving Statistics ........................................................... 10 

2.3.15 EXT, External Trigger ................................................................. 11 

2.3.16 MENU ........................................................................................... 11 

2.3.17 ENTER .......................................................................................... 11 

2.3.18 ESC, Escape ................................................................................. 11 

2.3.19 , , , Adjust..................................................................... 11 

2.4 Menu Level Functions ............................................................................ 12 

2.4.1 Menu Access and Movement ..................................................... 12 

2.4.2 Data Store .................................................................................... 14 

iv

2.4.3 Meter Configuration ................................................................... 15 

2.4.4 Auto Cal ....................................................................................... 16 

2.4.5 User Calibration .......................................................................... 17 

2.4.6 DC Sampling ................................................................................ 17 

2.4.7 Trigger Output ............................................................................ 18 

2.4.8 Trigger Input ............................................................................... 19 

2.4.9 Bar Graph .................................................................................... 19 

2.4.10 Tone ............................................................................................. 20 

2.4.11 Detector Switch Position............................................................ 20 

2.4.12 Remote Setup .............................................................................. 20 

2.4.13 General Information Functions .................................................. 20 

2.5 Connecting AC Power ............................................................................. 21 

2.6 Detector Connection and Setup............................................................. 22 

2.7 Power Up ................................................................................................. 22 

2.8 Performing Basic Measurements ........................................................... 23 

2.8.1 Making a DC Power Measurement ............................................ 23 

2.8.2 Making a Peak-to-Peak Power Measurement ............................ 23 

2.8.3 Making a Pulse Energy Measurement ....................................... 24 

2.8.4 Making a Signal Integration Measurement................................ 24 

2.8.5 Measuring a Laser Pulse Energy with a Thermopile Detector 24 

2.8.6 Using the Model 1835-C as an Exposure Controller ................. 26 

Section 3 – Principles of Operation 

3.1 Introduction ............................................................................................ 27 

3.2 Analog Signal Flow .................................................................................. 27 

3.3 Digitized Signal Flow ............................................................................... 28 

3.4 Typical Detector Signals......................................................................... 30 

3.5 Thermopile Detector Signals ................................................................. 30 

3.6 Pulse Energy Detector Signals ............................................................... 31 

3.7 Peak-to-Peak (Photodiode) Detector Signals ........................................ 32 

3.8 Integration of Detector Signals .............................................................. 33 

3.9 Analog Output ......................................................................................... 34 

3.10 Measurement Considerations ................................................................ 34 

3.10.1 Detector Calibration and Accuracy ........................................... 34 

3.10.2 Quantum Detector Temperature Effects .................................. 35 

3.10.3 Thermopile Detector Temperature Effects .............................. 35 

3.10.4 Energy Detector Temperature Effects ...................................... 35 

3.10.5 Ambient and Stray Light ............................................................ 35 

3.10.6 Common Measurement Errors .................................................. 36 

Section 4 – Computer Interfacing 

4.1 General Guidelines .................................................................................. 37 

4.2 Computer Interface Terminology .......................................................... 37 

4.3 Entering Remote Computer Interface Mode ......................................... 39 

4.4 RS-232C Communication ........................................................................ 39 

4.4.1 Setting Baud Rate and Echo Mode from the Keypad. .............. 40 

4.4.2 Setting Baud Rate and Echo Mode from a Remote Interface .. 40 

v

4.5 RS-232C XON/XOFF Handshaking Protocol .......................................... 41 

4.6 GPIB Communication ............................................................................. 41 

4.6.1 Setting the GPIB Address ........................................................... 42 

Section 5 – Remote Command Reference 

5.1 Model 1835-C Remote Interface Commands ......................................... 43 

5.2 Device Independent Commands ............................................................ 45 

5.3 Device Dependent Commands............................................................... 54 

Section 6 – Maintenance, Test and Troubleshooting 

6.1 Maintenance Procedures ....................................................................... 82 

6.2 Power Up Self Test .................................................................................. 82 

6.3 Troubleshooting Guide .......................................................................... 82 

Section 7 – Factory Service 

7.1 Introduction ............................................................................................ 85 

7.2 Obtaining Service .................................................................................... 85 

Service Form ........................................................................................... 87 

Appendices 

A Syntax and Definitions ............................................................................ 89 

B Error Messages ....................................................................................... 93 

C Status Reporting System ........................................................................ 96 

D Sample Programs .................................................................................. 100 

vi

List of Figures 

1. Model 1835-C Controller and Accessories ..................................................... 1 

2a. Model 1835-C VFD Display .............................................................................. 3 

2b. Description of Model 1835-C Display Regions ............................................... 4 

3. Front Panel Key Pad ........................................................................................ 5 

4. Decimal Point Indication of Menu Hierarchy Position ................................ 12 

5. Rear Panel Power Supply Voltage Switches in Positions L, R .................... 21 

6. Connecting a Detector with its Calibration Module .................................... 22 

7. Model 1835-C Detector Calibration Module Input Port .............................. 22 

8. Measuring Laser Pulse Energy via a Thermopile in INTG Mode ................ 25 

9. Model 1835-C Analog Signal Flow Diagram .................................................. 27 

10. Model 1835-C Digitized Signal Flow Block Diagram..................................... 28 

11. Thermopile Signals ........................................................................................ 30 

12. Energy Detector Signal from a Single Optical Pulse .................................... 31 

13. Negative Baseline Drift Voltage to a Pulse Train ......................................... 31 

14. Time Varying Signal Measurements ............................................................. 32 

15. Integrated Energy Via a Trapezoid Approximation .................................... 33 

16. Measuring Laser Pulse Energy with a Thermopile...................................... 34 

17. RS 232 Cable Connections ............................................................................. 40 

vii

List of Tables 

Table 1. Model 1835-C Display Annunciators .................................................... 4 

Table 2. Model 1835-C Top Level Key Functions and 

Associated Remote Commands ........................................................... 5 

Table 3. Newport Detector Families and Available Measurement Modes ...... 9 

Table 4. Model 1835-C Measurement Modes ..................................................... 9 

Table 5. Valid Display Units Available to Detector Families by MODE.......... 10 

Table 6. Displayed Unit Abbreviations versus Actual Measurement Units .. 10 

Table 7. Menu Level Key Functions and Parameters ...................................... 13 

Table 8. Data Store Operations ......................................................................... 14 

Table 9. Configuration Parameters and Default Conditions ........................... 15 

Table 10. Meter Configuration Operations ........................................................ 16 

Table 11. User Calibration Operations ............................................................... 17 

Table 12. SAMPLE PREC States and Limits ........................................................ 18 

Table 13. DC SAMPLING Operations .................................................................. 18 

Table 14. TRIGGER OUT Operations .................................................................. 19 

Table 15. EXT TRIGGER IN Operations .............................................................. 19 

Table 16. BAR GRAPH Operations ...................................................................... 19 

Table 17. TONE Operations ................................................................................ 20 

Table 18. DET SWITCH POS Operations ............................................................ 20 

Table 19. REMOTE SETUP Operations ............................................................... 20 

Table 20. GENERAL INFO Operations ................................................................ 21 

Table 21. Power Supply Voltage Switch Positions ............................................ 21 

Table 22. Analog Signal Flow Paths .................................................................... 28 

Table 23 Common Measurement Errors ........................................................... 36 

Table 24 Model 1835-C IEEE-488.1 Capabilities Summary ............................... 41 

Table 25 Device Independent Status Commands ............................................. 43 

Table 26 Device Dependent Commands .................................................... 44 - 45 

Table 27. Symptom/Fault Troubleshooting Guide ..................................... 83 - 84 

viii

Safety Symbols and Terms 

The following safety terms are used in this manual: 

The WARNING heading in this manual explains dangers that could result in 

personal injury or death. 

The CAUTION heading in this manual explains hazards that could damage 

the instrument. 

In addition, a NOTES heading gives information to the user that may be 

beneficial in the use of this instrument. 

GENERAL WARNINGS AND CAUTIONS 

The following general warnings and cautions are applicable to this 

instrument: 

WARNING 

This instrument is intended for use by qualified personnel who recognize 

shock hazards or laser hazards and are familiar with safety precautions 

required to avoid possible injury. Read the instruction manual 

thoroughly before using, to become familiar with the instrument’s 

operations and capabilities. 

WARNING 

The American National Safety Institute (ANSI) states that a shock hazard 

exists when probes or sensors are exposed to voltage levels greater then 

42VDC or 42V peak AC. Do not exceed 42V between any portion of the 

Model 1835-C (or any attached detector or probe) and earth ground or a 

shock hazard will result. 

CAUTION 

There are no user serviceable parts inside the Model 1835-C. Work 

performed by persons not authorized by Newport may void the warranty. 

For instructions on obtaining warranty repair or service please 

refer to Section 5 of this manual. 

ix

Definitions 

A amps 

AC alternating current 

ADC analog-to-digital converter 

BAT battery option 

BIC biconic fiber connector 

BNC standard coaxial connector type 

°C degrees Centigrade 

DC direct current 

°F degrees Fahrenheit 

Hz hertz (cycles per second) 

I-V current-to-voltage converter 

kHz kilohertz 

kΩ kiloOhms 

mA milliamps 

mV millivolts 

nA nanoamps 

nF nanofarads 

nm nanometers 

P-P peak-to-peak 

RH relative humidity 

S/N serial number 

µA microamps 

µS microsecond 

V volts 

W watts 

x

Specifications 

Physical Specifications: 

Dimensions: 

Weight: 

Enclosure: 

Connectors: 

Power: 

Display: 

Display Update Rate: 

Gain Ranges: 

Operating Environment: 

Storage Environment: 

Compatible Detectors: 

4.2 × 8.8 × 13.9 in (107 × 224 × 353 mm) 

8 lb, 3 oz. (3.7 kg) 

Metal case, painted 

8-Pin Sub Mini DIN CAL MODULE Input; 

BNC Analog Output, Trigger Output and 

Trigger Input; 9 Pin D-Sub RS-232, 

24 Conductor GPIB 

100/120/220/240 VAC ± 10%, 50/60 Hz 

5.5 digit annunciated VFD 

10 Hz 

Up to 7 decades (Detector and MODE 

dependent) 

0°C – 40°C; < 70% RH noncondensing 

-20°C – 60°C; < 90% RH noncondensing 

Low-Power (Semiconductor) Family 

High-Power (Thermopile) Family 

Energy (Pyroelectric) Family 

xi

Electrical Specifications: 

DC Current Measurement (Low-Power, Semiconductor Photodiode CAL MODULE) 

Signal Range: 1,2 0 1 2 3 4 5 6 

Full-Scale Current: 2.51 nA 25.1 nA 251 nA 2.51 µA 25.1 µA 251 µA 2.50 mA 

A/D Resolution: 126 FA 1.26 pA 12.6 pA 126 pA 1.26 nA 12.6 nA 126 nA 

(20,000 Count Precision) 

Display Noise Floor: ≤ 8 LSD ≤ 1 LSD ≤ 1 LSD ≤ 1 LSD ≤ 1 LSD ≤ 1 LSD ≤ 1 LSD 

(Input Open, Filter Off) 

Full-Scale Accuracy: 3 ± 0.1% 0.05% 0.05% 0.05% 0.05% 0.05% 0.05% 

(Typical) 

Full-Scale Accuracy: 3 ±0.48% .30% .30% .30% .30% .30% .30% 

(Worst-Case) 

Peak-Peak Current Measurement (Low-Power, Semiconductor Photodiode CAL MODULE) 

Signal Range: 1, 2 0 1 2 3 4 5 6 7 8 

Full Scale (P-P) Current: 253 nA 797 nA 2.52 µA 7.97 µA 25.1 µA 79.3 µA 251 µA 793 µA 2.51 mA 

A/D Resolution: 61.7 pA 195 pA 616 pA 1.95 nA 6.13 nA 19.4 nA 61.3 nA 194 nA 613 nA 

Full-Scale Accuracy: 3 ±1% ±1% ±1% ±1% ±1% ±1% ±1% ±1% ±1% 

(Typical) 

Full-Scale Accuracy: 3 ±2% ±2% ±2% ±2% ±2% ±2% ±2% ±2% ±2% 

(Worst Case) 

Bandwidth (3db): (5 Hz - 1 KHz) (5 Hz - 10 KHz) (5 Hz - 47 KHz) 

Frequency Range for 

±2% (Typ) Accuracy: (50 Hz - 100 Hz) (50 Hz - 1.4 KHz) (50 Hz - 7 KHz) 

Trigger Level: 4% of full scale (fixed) above ground. 

D.C. Voltage Measurement (Thermopile CAL MODULE) 

Signal Range: 1, 2 0 1 2 3 

Full Scale Voltage: 2.49 mV 24.9 mV 249 mV 2.49 V 


Resolution: 125 nV 1.25 µV 12.5 µV 125 µV 


Display Noise Floor: ≤ 8 LSD ≤ 1 LSD ≤ 1 LSD ≤ 1 LSD 

(Input Shorted) 

Full Scale Accuracy (Typ.): 3 ± .3% ± .2% ± .1% ± .05% 

Full Scale Accuracy: ± .56% ± .36% ± .18% ± .1% 

(Worst Case) 

Bandwidth (3db): 5 Hz 5 Hz 5 Hz 5 Hz 

1 

Listed signal ranges specify meter capability. Available signal ranges are detector dependent. 

2 

Maximum measurable signal is detector dependent. See description of detector saturation message “SA”, page 83. 

3 

After 60 min warm-up, followed by execution of AUTOCAL command. See Section 2.4.4. 

xii

Pulse Voltage Measurement (Energy, Pyroelectric CAL MODULE) 

Signal Range: 1 0 1 2 3 4 5 6 7 8 9 

Full Scale 2 Voltage: 789 µV 2.50 mV 7.89 mV 25.0 mV 78.9 mV 250 mV 789 mV 2.50 V 7.91 V 25.0 V 

A/D Resolution: 193 nV 610 nV 1.93 µV 6.10 µV 19.3 µV 61.0 µV 193 µV 610 µV 1.93 mV 6.10 mV 

Full-Scale Accuracy: 3 ±1% ±1% ±1% ±1% ±1% ±1% ±1% ±1% ±1% ±1% 

(Typical) 

Full-Scale Accuracy: 3 ± 2% ± 2% ± 2% ± 2% ± 2% ± 2% ± 2% ± 2% ± 2% ± 2% 

(Worst Case) 

Maximum Pulse Repetition Rate: 2 kHz 

Trigger Level: 8% of Full Scale 1 (fixed) 

1 

Listed signal ranges specify meter capability. Available signal ranges are detector dependent. 

2 

Full scale voltage is measured relative to baseline voltage. 

3 

After 60 min warm-up, followed by AUTOCAL command. See Section 2.4.4. 

Analog Output 

Full Scale Voltage: 0 - 2.5V into 50Ω 

Accuracy: ± 2.5% 

xiii

Detector Signals and Calculations: 

S 

Represents the most recent signal value obtained 

from the A/D converter. It may represent 

amps or volts and may be analog and or digitally 

filtered. 

S d 

Represents the value stored as a reference signal 

for subsequent use in signal offset, i.e. ZERO 

calculations. Sd=0 when ZERO is off. 

S− 

S d 

( S− 

Sd) 

R 

λ 

10 log ⎜ 

⎝ 

⎛ ( ) d 

( S− 

Sd)/ Rλ 

STO-REF 

S− 

S / R 

1mW 

⎛ ( ) 

λ 

⎞ 

⎟ 

⎠ 

S− 

S / R ⎞ 

d λ 

10 log ⎜ 

⎟ 

⎝ STO-REF ⎠ 

Represents the most recent net signal value. 

This is the value that is displayed when units are 

set to Amps or Volts. Note that Sd = 0 when 

ZERO is off. 

Measurement calculation when the display units 

are Watts or Joules. R λ is the detector 

responsivity associated with the current wavelength 

setting. 

Measurement calculation when the display 

units are ten times the (base ten) logarithm of the 

ratio of the measured power to 1 mW, i.e. dBm. 


are the ratio of measured power to the value 

stored by the STO-REF function. 


are ten times the (base ten) logarithm of the 

ratio of measured power to the value stored by 

the STO-REF function. 

xiv

■ Model 1835-C 

INPUT 

Section 1 

General Information 

1.1 System Overview 

The Model 1835-C Multi-Function Optical Meter is a high performance instrument 

with a wealth of measurement and triggering features designed to 

provide measurement sensitivity, flexibility and speed. In spite of its power, 

Model 1835-C is also designed to provide simple operation with direct panel 

access to basic features and a shallow menu for access to advanced features. 

Great flexibility exists within the command structure of the Model 1835-C so 

that even complex measurements can be set up quickly and easily. The 1835-C 

can react to or provide triggering, act as an exposure or noise meter, or data log 

up to 2,500 measurements! 

The Model 1835-C is compatible with all of Newport’s Low-Power, High-Power 

and Energy detector families. A family tree of the 1835-C, compatible detectors 

and accessories is shown in Figure 1 below. 

818T-10/CM 

818T-30/CM 

818T-150/CM 

818T-150X/CM 

FP3-FH1 

818J-S10/CM 

818J-09/CM 

818J-09B/CM 

818J-25/CM 

818J-25B/CM 

818J-50/CM 

818J-50B/CM 

818-UV/CM 

818-SL/CM 

818-IR/CM 

818-FA3-SMA 

818-FA3-ST 

818-FA3-FC 

818-FA2 

818-ST/CM 

818-F-SL 

818-F-IR 

■ Multi-Function Optical Meter 

Figure 1. Model 1835-C Controller and Accessories 

The Model 1835-C connects to detectors through a calibration module containing 

information unique to the detector being used. Calibration modules 

are ordered with a detector at the time of purchase and are labeled with the 

detector’s model number and serial number. Detectors with calibration 

modules have a “/CM” appended to their model number. 

EXAMPLE: 818-SL (no calib. module) 818-SL/CM (with calibration module) 

1

1.2 Scope of this manual 

Please carefully read this instruction manual before using the Model 1835-C 

Multi-Function Optical Meter. Be especially careful to observe the warnings 

and cautions throughout this manual. If any operating instructions are not 

clear, contact Newport Corporation. 

This instruction manual contains the necessary information for operation and 

maintenance of the Newport Model 1835-C Multi-Function Optical Meter as 

well as information for troubleshooting and obtaining service if necessary. 

This information is divided into the following sections: 

Section 1 

General Information and Functional Description 

Section 2 

System Operation 

Section 3 

Principles of Operation 

Section 4 

Computer Interfacing 

Section 5 

Computer Command Reference 

Section 6 

Maintenance and Troubleshooting 

Section 7 

Factory Service 

Appendix A 

Syntax and Definitions 

Appendix B 

Error Messages 

Appendix C 

Status Reporting System 

1.3 Unpacking and Inspection 

All Model 1835-C Multi-Function Optical Meters are carefully assembled, 

tested and inspected before shipment. Upon receiving this instrument, check 

for any obvious signs of physical damage that might have occurred during 

shipment. Report any such damage to the shipping agent immediately. Retain 

the original packing materials in case reshipment becomes necessary. 

1.4 Preparation for Use 

The Model 1835-C Multi-Function Optical Meter should have some operations 

performed before measurements are made. These include: 

Connecting AC Power (Section 2.5) 

Detector Connection and Setup (Section 2.6) 

1.5 Optional Accessories and Services 

The Newport Catalog presents up to date information on the detectors, 

detector accessories and detector calibration services available for use with 

the Model 1835-C Multi-Function Optical Meter. Refer to Figure 1 for where a 

given detector or accessory fits within the Model 1835-C family tree. 

2

Section 2 

System Operation 

2.1 Introduction 

The Model 1835-C is designed to provide quick operation and to avoid a steep 

learning curve. This section starts by giving a brief listing of display, key pad 

and menu command features. Much of the Model 1835-C’s operation will be 

obvious after these descriptions. The manual then explains each key operation 

and menu command in detail. Reference each of these detailed explanations 

as required when getting started. 

2.2 Display 

The Model 1835-C incorporates a vacuum fluorescent display, VFD, which can 

be clearly observed with most laser goggles and at high angles of incidence. 

Figure 2 illustrates and identifies the primary regions and annunciators within 

the Model 1835-C’s display. 

Figure 2a. Model 1835-C VFD Display 

3

Measurement 

Activity 

Annunciator 

Measurement Display Area 

Units Display 

Measurement 

Mode 

Annunciators 

MODE 

= P-P DC INTG SNGL CONT PULSE FLTR = ANLG + DIG 

Bar Graph, Menu and Message Display Area 

Signal Filtering 

Annunciators 

SHIFT MENU EDIT STORE USRCAL EXT ATTN ZERO AUTO 

Status 

Annunciators 

Figure 2b. Description of Model 1835-C Display Regions — 

Annunciator 

DC 

INTG 

P-P 

SNGL 

CONT 

PULSE 

ANLG 

DIG 

SHIFT 

MENU 

STORE 

USRCAL 

EXT 

AUTO 

ZERO 

ATTN 

Table 1. Model 1835-C Display Annunciators 

Comment 

Blinking indicates that the meter is making measurements. 

Meter is set to make DC signal measurements. 

Meter is set to make INTEGRATED signal measurements. 

Meter is set to make Peak-to-Peak signal measurements. 

Meter will make only one measurement per front 

panel or external trigger. 

Meter will continuously make measurements until 

stopped. 

Meter is set to make pulse energy measurements. 

Analog signal filtering is on. 

Digital signal filtering is on. 

Indicates that the next key press will execute a blue 

key function. 

Meter and display are in menu mode. Measurement 

is stopped. 

Meter is logging measurements into memory, i.e. 

data logging. 

User (versus calibration module) has supplied the 

detector responsivity in use. 

External trigger input is enabled. 

Automatic signal gain ranging is on. 

Background signal subtraction, (zeroing), is on. 

The responsivity in use includes the affect of the 

detector’s attenuator. 

4

2.3 Top Level Key Functions 

Operating controls for the Model 1835-C are found on both the front and rear 

panels of the Model 1835-C. For measurement operation, only the front panel 

controls are used. Rear panel controls are used for AC line power setup, 

Section 2.5. 

The front panel key pad of the Model 1835-C, Figure 3, provides quick access 

to measurement functions and menu access to advanced features and setup 

parameters. Table 2 and Sections 2.3.1 through 2.3.12 list and describe each 

top level key function. Menu level key functions are discussed in Section 2.4. 

(LOCAL) 

SHIFT 

STO REF 

DISP 

ATTN 

FILTER 

λ 

ZERO 

RANGE 

AUTO 

O 

I 

EXT 

R/S 

MENU 

MODE 

ENTER 

UNITS 

ESC 

STATS 

5 

Figure 3. Front Panel Key Pad 

Table 2. Top Level Key Functions and Associated Remote Commands 

Keypad Remote Commands Description 

O I 

None 

Turn the Model 1835-C on and 

off. 

SHIFT None Enable the blue key functions. 

DISP DISP, DISP? Cycle display brightness: OFF, 

LOW, NORM and HIGH. 

FILTER FILTER, FILTER? Cycle signal filtering: OFF, 

ANLG, DIG and ANLG+DIG. 

ZERO ZERO, ZERO?, STOZERO, Zero the display via offset 

ZEROVAL? 

subtraction. 

AUTO AUTO, AUTO? Turn automatic gain ranging on 

and off. 

STO REF STOREF, STOREF? Store last reading for future dB 

and REL measurements. 

ATTN ATTN, ATTN? Set responsivity to detector or 

detector-with-attenuator. 

λ LAMBDA, LAMBDA? Display and edit the calibration 

wavelength in use. 

RANGE RANGE, RANGE? Display signal gain range in use. 

R/S RUN, STOP Starts and stops signal 

acquisition. 

MODE MODE, MODE? Cycle meter between allowed 

measurement modes. 

UNITS UNITS, UNITS? Cycle display measurement 

units between those allowed. 

STATS STSIZE, STSIZE?, STMAX? Display statistics.: Max, Min, 

STMIN?, STMXMN? STMEAN Max-Min, Mean and Std. Dev. 

STSDEV?

EXT EXT Enable or disable external 

triggering. 

MENU None Enter or exit MENU command 

mode. 

ENTER None Select next lower menu level or 

enter edit mode. 

ESC None Escape to next higher menu 

level or escape edit mode. 

, None Adjust gain range or parameter 

values or move through a list. 

, None Zooms bargraph in or out. When 

in Edit mode, selects the digit to 

be edited by the , keys. 

2.3.1 

O 

I 

, Power 

The O I key toggles the Model 1835-C on and off. To turn the meter on, 

O I 

depress the key in until it clicks and stays in its depressed position. To 

turn the meter off, press the key again until it clicks and rebounds to its 

original length. 

2.3.2 SHIFT 

When SHIFT is pressed, the SHIFT display annunciator lights and the blue key 

functions (such as STOREF) are enabled. The next key press will cause that 

blue function to be executed and the “shift status” to disable. If a no blue 

function is the next pressed, then the ‘shift status’ reverts to disabled. 

2.3.3 DISP , Display Brightness 

This key cycles the display and the backlit key pad through: OFF, LOW, 

NORM and HIGH brightness levels. This allows a user to operate in a dark 

environment without light pollution from the display, (except for one dim 

scanning decimal point and the measurement activity annunciator). 

When the display is OFF, the R/S key may be used to manually trigger measurements. 

Any other key press returns the display to the LOW brightness 

state while ignoring the key function. 

2.3.4 FILTER, Signal Filtering 

Press this key to cycle input signal filtering between: OFF, ANLG, DIG, 

ANLG+DIG. This function provides methods of lowering the noise observed in 

the measurement data and the analog output. 

When the ANLG annunciator is lit, a 5Hz low pass filter lowers the noise floor 

by attenuating high frequency signal components. ANLG filtering is not 

available to High Power detectors, Energy detectors or any P-P modes. 

When the DIG display annunciator is lit, measurements pass through a moving 

10-sample averaging buffer before being further processed, stored or communicated 

to the display or computer interfaces. With DIG on, all observable 

values represent digitally averaged results relative to the original A/D conversions. 

This averaging is independent of the subsequent processing available 

through the STATS buffer, Section 2.3.14. 

6

2.3.5 ZERO, Offset Subtraction 

This key turns offset subtraction on and off. When turned on, the ZERO 

annunciator lights and the last signal reading is saved as S d 

and subtracted 

from all subsequent signal readings S. This causes subsequent signal calculations 

(and the display) to use the value S-S d 

instead S. 

Offset subtraction allows one to remove the effects of ambient DC signals, by 

zeroing the display before making a measurement. A second ZERO key press 

turns off the ZERO annunciator and stops offset subtraction. 

2.3.6 AUTO, Automatic Gain Ranging 

The AUTO key toggles automatic signal ranging on and off. When on, the 

AUTO annunciator lights and the signal range (amplifier gain) is adjusted to 

utilize maximum analog-to-digital converter resolution. When AUTO is turned 

off, the AUTO annunciator is turned off and the signal range is left in its 

current state. 

Signal range can be manually controlled by the , arrow keys. Pressing an 

, arrow key when AUTO is on (and STATS, MENU and λ are off), turns 

AUTO off and executes the manual range change. See RANGE, Section 2.3.10. 

Signal range changes will not often coincide with observable changes to the 

display value as the display is scaled by the detector responsivity and so must 

adjust independently. Signal range gains will occur in 1 decade steps when 

auto ranging and 1 or 1 ⁄2 decade steps (depending on MODE) when manual 

ranging. 

When auto ranging in CONT PULSE mode, the arrival rate of pulses must be 

above 1 Hz. In P-P CONT mode, the arrival rate of peaks must be above 50 Hz. 

AUTO gain ranging is not allowed in SNGL measurement modes. When exiting 

a SNGL measurement MODE, AUTO will turn back on if it was on when the 

SNGL measurement mode was entered. (See MODE, Section 2.3 12) 

2.3.7 STO REF, Store Reference Value 

STO REF causes the last measurement D to be stored as D ref 

for subsequent 

use in relative measurement calculations. When units are relative, REL, the 

displayed value is the ratio D/D ref. 

When units are logarithmic relative, dB, the 

displayed value is the function 10 log (D/D ref 

). D ref 

is always a power reading 

stored in the units of Watts. 

Press STO REF to cause a new D ref 

to overwrite the existing D ref 

value and show 

this new D ref 

in the message display area. D ref 

will be displayed until overridden 

by an ESC, λ, RANGE or MENU keypress. STO REF can be pressed at any 

time. 

NOTE 

When not using remote interface operation and when displaying relative dB 

or REL measurements, the message display area will show the STO REF value 

used in the calculation. 

7

2.3.8 ATTN, Attenuator 

The ATTN key toggles the responsivity value, R λ 

, between the value for the 

detector alone and the value for the detector-with-attenuator. When ATTN is 

on, the ATTN annunciator is lit and the responsivity of the detector-withattenuator 

is used. When ATTN is off, the annunciator is off and the detectoralone 

responsivity is used. If the detector does not have an attenuator, or if 

USR CAL is on (Section 2.4.5) the ATTN key has no effect. 

2.3.9 λ, Wavelength 

A detector calibration module contains responsivity data for its assigned 

detector at discrete wavelengths. By telling the meter which wavelength is 

being measured, the correct responsivity value is used in calculating the 

measured power or energy. When a wavelength falls between two calibration 

points, linear interpolation is used to approximate the true responsivity value. 

Press the λ key to display the measurement wavelength in the message 

display area. Press ENTER to light the EDIT annunciator and cause the last 

digit of the wavelength to blink. Press , to adjust the blinking digit up 

or down and , to change which digit blinks. Press the ENTER a second 

time to accept the new wavelength and exit the wavelength edit/display mode. 

Press λ or ESC to exit without changing the wavelength. 

2.3.10 RANGE, Signal Range 

RANGE key allows the user to view the amplifier signal range. Signal ranges step 

in 1 or 1 ⁄2 decade gain increments (MODE dependent) as the RANGE is changed 

in order to utilize maximum resolution from the meter’s analog-to-digital 

converters. The available signal ranges are detector and mode dependent. 

Press RANGE to display the signal range number in the message display area. 

If AUTO is on, then the signal range number will change if the detector signal 

varies more than a decade in magnitude. Signal range changes can occur 

without an effect on the displayed measurement value. Press RANGE a 

second time to exit the signal range display mode. 

Press the , arrow keys to increase or decrease the signal range. If AUTO 

is on, pressing the , arrow keys will disable AUTO and cause the signal 

range to change. Manual ranging is useful when working with external analog 

recording equipments. 

NOTE 

Pressing the , arrow keys will disable AUTO ranging and change the 

signal range even when the signal range is not being displayed via the 

RANGE key. 

2.3.11 R/S, Run-Stop 

The R/S run-stop key provides front panel control over data acquisition. 

When in SNGL measurement mode, each R/S key press causes one reading to 

be taken. In CONT measurement mode, each R/S key press toggles continuous 

data acquisition on and off. 

The activity annunciator (Figure 2b) flashes to indicate that readings are being 

taken. A steady glow indicates that the meter is armed and waiting for a pulse 

or P-P waveform to arrive. The indicator is off when data acquisition has been 

stopped. 

8

2.3.12 MODE, Measurement Mode 

The Model 1835-C provides a number of measurement modes for acquiring 

data. At power on, the meter checks the detector’s calibration module to 

determine which measurement modes the detector supports. Table 3 describes 

the measurement modes available for each family of detector. 

Table 3. Newport Detector Families and Available Measurement Modes 

Low-Power High-Power Energy 

DC CONT X X 

DC SNGL x x 

INTG x x 

P-P CONT 

x 

P-P SNGL 

x 

CONT PULSE 

X 

SNGL PULSE 

x 

X marks the default mode for the detector family 

Press the MODE key repeatedly until the desired mode is indicated in the 

mode annunciator area of the display, see Table 4. When selecting a new 

mode, the display units will change to appropriate default units if they are not 

compatible with the new measurement mode, Section 2.3.13. 

Mode 

DC CONT 

DC SNGL 

INTG 

P-P CONT 

P-P SNGL 

CONT PULSE 

SNGL PULSE 

Table 4. Model 1835-C Measurement Modes 

Description 

Measurement occurs at a programmable sample rate, 

Section 2.4.6. 

A measurement is taken every time the meter receives a 

trigger up to a 1000Hz. rate. (AUTO is disabled in SNGL 

mode.) 

Measurements occur at 500Hz and are trapezoidally 

integrated to get an energy result. An R/S key press or 

external trigger sets the display to 0.0000 and sampling 

starts. A second R/S keypress or external trigger terminates 

integration. 

Acquisition is driven by the arrival of high-low peak 

pairs. A measurement is processed for every high-low 

peak pair up to a frequency of 1000 Hz. Above 1000 Hz, 

pair captures experience a minimum 1 ms separation. 

A trigger 1 arms the meter to capture the next high-low 

peak pair. Triggers can occur at a rate of up to 1000 Hz. 

(AUTO is disabled in SNGL mode.) 

The meter captures every energy pulse up to a frequency 

of 1000 Hz. Above 1000 Hz, pulse acquisitions experience 

a minimum 1 ms separation. 

A trigger 1 arms the meter to capture the next energy 

pulse. Triggers can occur at a rate of up to 1000 Hz. 

(AUTO is disabled in SNGL mode.) 

9

1 

“Trigger” refers to a command to start or stop signal acquisition. Trigger 

sources are the R/S key, the external trigger input and remote interface 

commands. 

2.3.13 UNITS, Display Units 

Measurements can be displayed in various units. The set of units available at 

any given time is determined by the detector type and the measurement 

mode. Press the UNITS key repeatedly to cycle the display units through the 

set of available units. Table 5 describes the sets of available units for each 

detector family as a function of the measurement mode. 

Table 5. Valid Display Units Available to Detector Families by MODE. 

FAMILY MODE V A W W/cm 2 J J/cm 2 Erg Erg/cm 2 dBm dB REL 

Low-Power DC CONT x X x x x x 

Low-Power DC SNGL x X x x x x 

Low-Power INTG X x x x 

Low-Power P-P CONT x X x x x x 

Low-Power P-P SNGL x X x x x x 

High-Power DC CONT x X x x x x 

High-Power DC SNGL x X x x x x 

High-Power INTG X x x x 

Energy CONT PULSE x X x x x x 

Energy SNGL PULSE x X x x x x 

X denotes the default units for the detector family in the given measurement 

mode. 

Some display units are abbreviated. Table 6 lists displayed units versus actual 

measurement units. Display units are limited to four characters in order to 

provide for display engineering prefixes such as: p, n, µ, m and k. (pico, nano, 

micro, milli and kilo respectively). 

Table 6. Displayed Unit Abbreviations Versus Actual Measurement Units. 

Actual Units V A W J Erg W/cm 2 J/cm 2 Erg/cm 2 dBm dB REL 

Displayed Units V A W J ERG W/cm J/cm E/cm dBm dB E±dd 

2.3.14 STATS, Moving Statistics 

The STATS key causes a list of statistical results from the stats buffer to be 

displayed in the message display area. The stats buffer is a moving data 

window containing the most recent measurements to a depth 1 ″ N ″ 100. The 

default value is N = 10. Display occurs without disrupting data acquisition or 

storage and results are continuously updated. 

Press the STATS key to enter the stats display list. The first statistic displayed 

will be the stats buffer depth N. Press the , adjust keys to move through 

the list. The following statistics are available: N, MAX, MIN, MAX-MIN, MEAN 

and STD DEV. 

When the STATS buffer depth, N, is displayed, it can be adjusted by pressing 

ENTER and using the , keys to set a new value for N. Press the ENTER 

key to adopt the new value for N and escape the edit mode. The STATS buffer 

is cleared whenever a new stats buffer depth N, or MODE or UNITS is established. 

Press the STATS key a second time to exit the stats display mode. 

10

2.3.15 EXT, External Trigger 

EXT enables and disables the triggering of data acquisition through the rear 

panel trigger input BNC connector. The meter can be configured to be 

triggered by either a rising or falling edge TTL signal. See Section 2.4.8. 

Press EXT to light the EXT annunciator and enable the external trigger input. 

The Model 1835-C will still respond to triggers from the R/S key even when the 

EXT trigger is enabled. Press the EXT key a second time to turn off the 

annunciator and disable the external trigger input. 

2.3.16 MENU 

The MENU key provides access to advanced features and parameters. Press 

the MENU key to stop all data acquisition, light the MENU annunciator, and 

display the first item of the top level menu list. Press the MENU key a second 

time to immediately exit the menu. Menu structure and functions are presented 

in Section 2.4. 

The menu consists of a series of lists and parameter values. Most parameter 

values can be edited to configure the meter. Lists are moved through via the 

, keys. To move to a lower level list, press the ENTER key. To escape a 

lower level list, press the ESC key. 

In the menu, all key functions are ignored except for the MENU, ENTER, ESC 

and the , keys. Each key will act without having to initially press SHIFT. 

Pressing SHIFT will toggle the SHIFT annunciator, but it will not effect anything 

else when in MENU mode. 

To edit a displayed parameter press ENTER. This enables the edit mode and 

causes the parameter (or a digit) to blink. Press the , keys to adjust the 

parameter through its allowed list or to count the blinking digit up and down. 

When adjusting a numerical value, the , keys can be used to change 

which decimal digit blinks. Press ENTER to adopt the new value and escape 

the editing mode. Press ESC to leave the editing mode without adopting the 

new value. 

2.3.17 ENTER 

ENTER allows one to move lower into the menu when in menu mode, to enter 

editing mode when an editable parameter is being displayed and to adopt a 

new parameter value after it has been edited. Editable parameters can be 

found both in and out of the menu mode. If ENTER is pressed when a noneditable 

parameter is being displayed, the key press is ignored. 

2.3.18 ESC, Escape 

ESC allows one to escape to the next higher level when in menu mode and to 

escape editing mode when editing a parameter value without adopting any 

changes to the parameter. At the top level of the menu, the ESC key causes 

one to escape menu mode. The ESC key also allows one to escape various 

other display modes such as STATS or wavelength display or amplifier signal 

gain range display modes. When there is nothing to escape from, the ESC key 

is ignored. 

2.3.19 , , , Adjust 

The , , , , keys allow one to adjust various parameter states and 

values. In normal operation, the , keys turn AUTO off and adjust the 

amplifier signal gain. In any other mode, the , keys cause one to move 

11

through a list or to adjust a blinking digit. The , keys zoom the bargraph 

( in, out) and in edit mode, select which digit of a numerical value will 

blink. 

2.4 Menu Level Functions 

Menu functions provide control over parameter values and methods of 

making measurements, The menu consists of a number of lists and parameter 

values. Table 7 presents a quick summary of the hierarchy of the menu 

functions and parameters. 

2.4.1 Menu Access and Movement 

To access the menu press MENU. The MENU annunciator will light and data 

acquisition will stop. 

Menu labels and parameter values are displayed in the message display area. 

The first, second and third leftmost decimal points within this area indicate a 

current position at the top, second, third or fourth level of the menu hierarchy, 

Figure 4. Table 7 presents the menu functions and their hierarchy. 

Top Level 

Second Level 

Third Level 

Fourth Level 

Figure 4. Decimal Point Indication of Menu Hierarchy Position 

In the menu, valid keys are limited to those needed to perform operations to 

move through the menu or edit a parameter value. In the menu, it is not 

necessary to hit the SHIFT key to invoke the action of the menu keys: MENU, 

ENTER, ESC or . , , , . The SHIFT key will toggle the SHIFT annunciator, 

but with no effect on subsequent pressings of other keys. Once in the 

menu, the rules for moving through the menu are as follows: 

i. Press ENTER to move to the next level down or to enter the edit mode if a 

editable parameter is being displayed and to accept a parameter value in 

its currently displayed state and exit edit mode. 

ii. Press ESC to move to the next level up or to escape the menu when at the 

top level or to exit edit mode without changing the parameter value being 

edited. 

iii. Press MENU to immediately escape the menu regardless of current level 

within the menu. 

iv. Use the , keys to move up or down through a menu list on a given 

level. Also use these keys to adjust a parameter or decimal value when in 

edit mode. 

v. Use the , keys to select the digit being adjusted when in edit mode. 

12

Table 7. Menu Level Key Functions and Parameters 

Top Level Second Level Third Level 

DATA STORE DATA STORE OFF DATA STORE ON, OFF 

CLR DATA BUFFER 

(or DATA BUFFER CLR) 

SLIDE BUFFER SLIDE, FIX BUFFER 

D_BUF SIZE dddd D_BUF_SIZE dddd 

VIEW DATA dddd OF dddd 

SAVE CONFIG SAVE TO d 

RECALL CONFIG RCL DEFAULT, d 

AUTO CAL 

DET SWITCH POS SWITCH POS S, I, L 

USER CALIB USR CAL OFF USR CAL ON, OFF 

USR RESP d.dddE±d A/W † 

PRESENT RESP d.dddE±d A/W † 

DC SAMPLING SAMPLE PREC PREC= 20000, 4096 

CNT 

SAMPLE FREQ FREQ = ddd.ddd HZ 

TRIGGER OUT TRIG ON CMPLT TRIG ON CMPLT, 

TRIG AT FREQ , 

TRIG ON LEVEL, 

TRIG ON INTG, 

TRIG OUT OFF 

TRIG POLARITY TRIG ACTIVE LO, HI 

TRIGGER FREQ FREQ= dddd.ddd HZ 

TRIGGER LEVEL LVL= ±d.ddd E±dd W 

TRIGGER INTG INTG= ±d.ddd E±dd J 

EXT TRIGGER IN FALLING , RISING EDGE 

BAR GRAPH ON BAR GRAPH ON, OFF 

TONE OFF TONE ON, OFF 

REMOTE SETUP GPIB ADDR dd GPIB ADDR dd 

BAUD RATE 9600 BAUD RATE 1200, 

2400, 4800, 9600, 

19.2K 

RS-232 ECHO OFF RS-232 ECHO ON, OFF 

GENERAL INFO MODEL 1835-C 

SW VERSION d.d 

DETECTOR INFO MODEL xxxxxx 

DET SN ddddd 

ATTN SN ddddd 

CAL ddMONyyyy 

† 

Units may be in A/W, V/W or V/J. 

Items in bold italics type are editable states or decimal values. Decimals are 

denoted by d. Move vertically via the , keys. Move horizontally via 

ENTER and ESC. 

13

2.4.2 Data Store 

The Model 1835-C allows a user to save up to 2500 measurements in an 

internal buffer for subsequent viewing or transmission over a computer 

interface. Data is maintained on power down, but lost when a new configuration 

is loaded, Section 2.4.3, or when the buffer is cleared via the CLR DATA 

BUFFER command or when data with new units is being stored. 

The data store buffer operates in two ways: SLIDE or FIX. In SLIDE configuration, 

the buffer slides along storing the most recent measurements up to the 

size of the buffer. Beyond this, as data enters the buffer, the oldest data is 

pushed out and lost. In FIX configuration, data storing continues until the data 

buffer is full. After this, data acquisition stops and no additional data can be 

stored without first clearing the buffer via the CLR DATA BUFFER command. 

DATA BUFFER CLR is displayed when the buffer is empty. 

The size of the buffer is set by the D_BUF_SIZE dddd menu function. Edit the 

value dddd to establish the number of data points that the buffer will hold 

before dropping old data or stopping data storage. 

Data storing is enabled by the user via the DATA STORE menu function. Edit 

the ON, OFF condition to enable or disable data storing and the associated 

STORE annunciator. 

When in CONT mode, data acquisition and storage is resumed immediately 

upon exiting the menu if acquisition was active as the menu was entered. 

When acquisition was not active when the menu was entered, or when in 

SNGL or INTG mode, data acquisition and storage requires an initiating R/S 

key press, external trigger or a remote RUN command after exiting the menu. 

Buffer data can be viewed via the VIEW DATA menu command. Data are 

displayed in the measurement area while the message area displays the 

position within the buffer: dddd of dddd. Use the , keys to move through 

the buffer data. The value dddd = 0001 is the first, i.e. the oldest datum. 

NOTE 

When DATA STORE is off, CONT acquisition mode behavior defaults to the 

condition where data acquisition is begun without the requirement of a 

starting trigger. SNGL acquisition modes always require a trigger for each 

acquisition. 

Table 8. Data Store Operations 

Menu Operation Keypad Commands Associated Remote Commands 

DATA STORE ON, OFF Edit ON, OFF status. DSE, DSE? 

DATA BUFFER CLR or 

CLR DATA BUFFER If CLR DATA BUFFER, DSCLR 

press ENTER to clear buffer. 

SLIDE, FIX BUFFER Edit SLIDE, FIX BUFFER DSBUF DSBUF? 

D_BUF_SIZE dddd Edit D_BUF_SIZE dddd DSSZ, DSSZ? 

VIEW DATA Press ENTER and use DS?, DSCNT?, DSUNITS? 

, keys. 

14

2.4.3 Meter Configuration 

The Model 1835-C provides a method to save the configuration of the meter 

and to recall that configuration for later use even if the meter has been turned 

off. This is accomplished through configuration buffers maintained in nonvolatile 

memory. Configuration buffers are numbered 0 to 9 with buffer 0 

being a DEFAULT buffer which can only be recalled but not saved to. The 

reset state of all the buffers except the default buffer is empty. Empty buffers 

cannot be recalled. 

A recalled configuration becomes the current configuration of the meter. Any 

changes to the current configuration must be saved via SAVE CONFIG or they 

will be lost when a new configuration is recalled. 

The meter will not recall a configuration that is not compatible with the 

detector calibration module currently plugged into the meter. Configurations 

using the same model of detector are compatible while configurations using 

different models of detectors are incompatible. 

The default configuration of the meter depends upon the detector family. The 

list of configuration parameters stored in a configuration buffer as well as 

their default values versus detector family are listed in Table 9 below: 

Table 9. Configuration Parameters and Default Conditions 

Parameter Detector Family Default Condition 

MODE Low-Power, High-Power DC CONT 

Energy 

CONT PULSE 

UNITS Low-Power, High-Power W 

Energy 

J 

λ, Lambda Lowest available 

PRESENT RESP 

PRESENT RESP 

USR CAL 

OFF 

ATTN 

OFF 

FILTER 

OFF 

DC SAMPLE PREC Low-Power, High-Power 20,000 CNT 

DC SAMPLE FREQ 

25 Hz 

AUTO 

ON 

RANGE 0 

ZERO 0.000 

Zero Value 0 

Reference Value 0.001 

STATS Buffer Size 10 

DET SWITCH POS Energy I, (Intermediate) 

DATA STORE 

OFF 

DATA STORE BUFFER 

SLIDE 

D_BUF_SIZE 100 

15

Parameter Detector Family Default Condition 

Data Store Units 

Same as UNITS 

EXT 

OFF 

EXT TRIG IN 

FALLING 

TRIGGER OUT 

TRIG ON CMPLT 

TRIG OUT POL 

TRIG ACTIVE LO 

TRIG OUT FREQ 

FREQ = 30 Hz 

TRIG LEVEL Low-Power, LVL = 0.001 W 

High-Power, Energy LVL = 0.001 J 

TRIG INTG LVL Low-Power, High-Power INTG = 0.001 J 

BAR GRAPH 

ON 

TONE 

OFF 

GPIB ADDR 05 

BAUD RATE 9600 

RS-232 ECHO 

OFF 

These parameters adopt the following default values at power up and are not 

affected by recalling a configuration or by setting the configuration to default. 

Local Lockout 

OFF 

Display Brightness 

NORMAL 

Table 10. below lists the menu commands effecting the saving and recalling of 

meter configurations. 

Table 10. Meter Configuration Operations 


SAVE CONFIG Adjust SAVE TO d, *SAV 

and ENTER 

RECALL CONFIG Adjust RECALL d, *RCL, *RST 

and ENTER 

2.4.4 AUTO CAL 

The AUTO CAL command causes the 1835-C to perform A/D conversions of 

amplifier offset voltages (zero errors) arising from aging and temperature 

effects. These conversions are then used in subtracting the appropriate error 

voltage from each reading during normal operation. The 1835-C automatically 

performs this procedure every time it powers up (or is reset). To achieve 

stable reading at the specified accuracy, AUTO CAL should be executed after a 

minimum 60 minute warm-up period from power-up. 

16

Executing AUTO CAL with High Power (Thermopile) detectors: 

1. With the detector connected to the 1835-C, remove the detector from the 

radiation source and allow a minimum of 60 seconds for the detector 

surface temperature to stabilize. 

2. Press ENTER when AUTO CAL is displayed. The display message area will 

display “ONE MOMENT”, followed by a buzzer sound indicating that AUTO 

CAL is complete. 

Executing AUTO CAL with Low Power (Photodiode) or Energy detectors: 

Simply press ENTER when AUTO CAL is displayed. The display message area 

will display “ONE MOMENT”, followed by a buzzer sound indicating that 

AUTO CAL is complete. Low Power and Energy detectors do no have to be 

connected to the 1835-C or removed from the radiation source to effectively 

execute AUTO CAL. 

2.4.5 User Calibration 

The Model 1835-C allows one to create a detector responsivity which overrides 

the responsivities obtained from the detector’s calibration module. This 

allows one to account for the effects of additional optics and filters in the 

measurement path. 

When USR CAL is on, the USR CAL annunciator is lit and the meter adopts the 

responsivity value displayed by the editable USR RESP value. Use the 

PRESENT RESP function to display the current calibration module 

responsivity. 

The USR RESP units are the same as the PRESENT RESP units. Table 11 lists 

the possible user calibration operations. 

Table 11. User Calibration Operations 


USR CALIB ON, OFF Edit USR CALIB USRCAL, USRCAL? 

ON, OFF 

USR RESP Edit d.dddE±dd A/W * USRRESP, USERRESP? 

PRESENT RESP ENTER to view RESP? 

d.dddE±dd A/W * 

* 

Units of A/W, V/W or V/J may be displayed. These units are not editable. 

2.4.6 DC Sampling 

The Model 1835-C incorporates two analog-to-digital, (A/D) converters, one 

with 20,000 count resolution and a second with 4096 count resolution. The 

user may select which A/D will be used during DC CONT and DC SNGL acquisition 

modes. All other modes use the 4096 count A/D. The 20,000 count A/D 

converter, can operate at sample rates up to 25 Hz. The 4,096 count A/D 

converter, can operate at sample rates up to 1000 Hz. 

The SAMPLE PREC menu command, Table 12, selects which analog-to-digital 

converter is used. Sampling frequency can be adjusted within the limits 

imposed by the SAMPLE PREC state, see Table 13. When the SAMPLE PREC 

state changes, the sampling frequency defaults to 25 Hz if the existing SAMPLE 

FREQ is incompatible with the new SAMPLE PREC state. 

17

Table 12. SAMPLE PREC States and Limits. 

SAMPLE PREC A/D Accuracy Sample Frequency Range 

20000 CNT 20,000 counts 0.001 Hz to 25.0 Hz 

4096 CNT 4,096 counts 0.001 Hz to 1000.0 Hz 

Table 13. DC SAMPLING Operations. 

Menu Function Keypad Commands Associated Remote Commands 

SAMPLE PREC Edit PREC= 20,000, SPREC, SPREC? 

4096 CNT 

SAMPLE FREQ Edit FREQ= SFREQ, SFREQ? 

ddd.ddd HZ 

2.4.7 Trigger Output 

The Model 1835-C’s rear panel TTL trigger output allows it to coordinate 

activities among other instruments. The trigger output can operate in several 

ways: conversion complete, periodic output, comparator output and integrating 

comparator output. In addition, the polarity of the trigger output can be 

specified. 

In TRIG ON CMPLT mode, a pulse is output after each reading has been 

acquired and completely processed. It indicates that the 1835-C is ready to 

take another reading. The width of this pulse is at least 8 µS. 

In TRIG AT FREQ mode, a pulse is output at a user defined frequency or rate. 

Each pulse width is at least 8 µS and the programmable frequency range of the 

pulses is 0.001 Hz to 1000.0 Hz. 

In TRIG ON LEVEL mode, each measurement is compared to a programmable 

trigger level. The units of the trigger level always equal Watts for power 

detectors or Joules for energy detectors. If a measurement is less than the 

specified value, then the trigger output is inactive. If the measurement 

exceeds the specified value then the trigger output becomes active. The TRIG 

ON LEVEL output is a shift in level rather than a pulse. 

In TRIG ON INTG mode, continuous measurements from a power detector are 

integrated and compared against a programmable value. The units of the 

programmable value are Joules. If the calculated integral is less than the 

specified value, then the trigger output is active. If the calculated integral 

exceeds the specified value, then the integration stops and the trigger output 

becomes inactive. The TRIG ON INTG trigger is a shift in level rather than a 

pulse. 

The polarity of the trigger output is programmable as active high or active 

low. If the polarity is active high then the output will idle low. If the polarity is 

active low then the line will idle high. 

18

Table 14. TRIGGER OUT Operations. 


TRIGGER OUT Edit TRIG ON CMPLT TRIGOUT, TRIGOUT? 

TRIG AT FREQ 

TRIG ON LEVEL 

TRIG ON INTG 

TRIG OUT OFF 

TRIG POLARITY Edit ACTIVE HI, LO TRIGOUTPOL, TRIGOUTPOL? 

TRIGGER FREQ Edit FREQ= ddd.ddd Hz TRIGOUTFREQ, TRIGOUTFREQ? 

TRIGGER LEVEL Edit LVL= d.dddE±dd W * TRIGOUTLVL, TRIGOUTLVL? 

TRIGGER INTG Edit INTG= d.dddE±dd J TRIGOUTINTG, TRIGOUTINTG? 

* 

Displayed units may be W or J depending upon the detector in use. 

2.4.8 Trigger Input 

The Model 1835-C’s rear panel TTL external trigger input can be enabled or 

disabled, Section 2.3.15, and have its edge polarity set. The edge polarity is 

accessed via the EXT TRIGGER IN menu function and can be set to rising or 

falling edge triggering. 

The external trigger (and R/S key) acts like an acquisition trigger when in 

SNGL modes and acts like a toggled acquisition gate when in CONT modes. In 

Peak-to-Peak or Pulse acquisition modes the external trigger (and R/S key) act 

as single or continuous acquisition enabled rather than forcing an acquisition 

to occur at the moment the trigger (or keypress) occurs. 

The external trigger pulse width must be ≥200 ns. In DC SNGL mode, the delay 

from the trigger input going active to the start of the A/D conversion is

2.4.10 Tone 

The 1835-C has a speaker that can emit a short tone or tick to indicate when a 

peak or pulse is detected in P-P or PULSE measurement modes. The audible 

output is enabled or disabled via the TONE menu function. TONE is not 

available in INTG measurement mode. 

Table 17. TONE Operations. 


TONE Edit TONE ON, OFF TONE, TONE? 

2.4.11 Detector Switch Position 

Some Newport Energy detectors have a switch that sets an electronic decay 

time constant to optimize operation for various pulse repetition rates. As this 

adjustment effects the responsivity of the detector, the Model 1835-C must be 

informed of the detector’s switch setting. The available detector switch 

settings are: SHORT, INTERMEDIATE and LONG. The 1835-C accounts for the 

switch setting through the DET SWITCH POS function. 

Table 18. DET SWITCH POS Operations. 


DET SWITCH POS Edit SWITCH POS DETSW DETSW? 

S, I, L 

2.4.12 Remote Setup 

The Model 1835-C provides both RS-232 and IEEE-488 computer interfaces as 

standard features. Each interface requires that certain parameters be set. 

Remote interface setup and commands are discussed in Section 2.5 Computer 

Interfacing. 

Table 19. REMOTE SETUP Operations. 


GPIB ADDR dd Edit GPIB ADDR dd None 

BAUD RATE dddd Edit BAUD RATE 1200, None 

2400, 4800, 9600, 19.2K 

RS-232 ECHO Edit RS-232 ECHO ECHO, ECHO? 

ON, OFF 

ON, OFF 

2.4.13 General Information Functions 

General information about the Model 1835-C and any attached detector can be 

found using the GENERAL INFO menu functions. These functions display the 

Model 1835-C software version, the detector’s model number, serial number, 

associated attenuator serial number and calibration date. 

20

Table 20. GENERAL INFO Operations. 


SW VERSION d.d For viewing only. *IDN? 

MODEL cccccccc For viewing only. DETMODEL? 

DET SN ddddd For viewing only. DETSN? 

ATTN SN ddddd For viewing only. ATTNSN? 

CAL ddMonyyyy For viewing only. CALDATE? 

2.5 Connecting AC Power 

The Model 1835-C can be configured to operate with line voltages over the 

following ranges: 90-264 VAC, 50-60 Hz. Before turning the meter on, configure 

it to local voltage using the following procedure: 

i. Configure the Model 1835-C’s power supply voltage selection switches to 

match the nominal local voltage. See Figure 5 and Table 21. 

ii. Plug an AC line power cord to the rear of the Model 1835-C and then 

connect the cord with AC power. 

50–60 Hz 

100 V 

120 V 

LINE 

SWITCH 1 SWITCH 2 

SELECT 

240 V 

220 V 

Figure 5. Rear Panel Power Supply Voltage Switches in Positions with Switch 

1 set to Left and Switch 2 set to Right 

Table 21. Power Supply Voltage Switch Positions. 

Switch 1 Position Switch 2 Position Nominal Local Voltage 

Right Right 100 VAC 

Right Left 120 VAC 

Left Right 220 VAC 

Left Left 240 VAC 

WARNING 

This product is equipped with a 3 wire grounding type plug. Any interruption 

of the grounding connection can create an electric shock hazard. 

If you are unable to insert the plug into your wall plug receptacle, 

contact your electrician to perform the necessary alterations to assure 

that the green (green-yellow) wire is attached to earth ground. 

21

2.6 Detector Connection and Setup 

Connect the detector to its calibration module as shown, Figure 6. The 

detector’s model and serial numbers should match the model and serial 

numbers found on the calibration module. Insert the calibration module into 

the front panel input port of the Model 1835-C. An alignment pin forces the 

proper orientation of the calibration module. 

Detector Cable BNC 

Calibration Module 

Figure 6. Connecting a Detector with its Calibration Module 

Plug calibration 

module into this port. 

INPUT 

Figure 7. Model 1835-C Detector Calibration Module Input Port 

NOTE 

If the detector being connected is a battery powered Newport Energy 

Detector then be sure to configure the DET SWITCH POS menu function to 

match the position of the switch on the detector, see Section 2.4.11. The 

1835-C defaults to the intermediate switch position, I. 

2.7 Power Up 

Turn on the Model 1835-C by depressing the front panel key until it clicks 

in and remains in its depressed position. The Model 1835-C will perform a 

power up self test, Section 6.2 and then configure itself to its last operating 

state. If the last operating state is not compatible with the current detector, 

the 1835-C adopts the default configuration appropriate to this new detector. 

If the meter does not pass its self test or fails to respond to front panel key 

commands, refer to Section 6, Maintenance and Troubleshooting. 

O 

I 

22

2.8 Performing Basic Measurements 

Basic measurement techniques for using the Model 1835-C are covered in the 

following sections. Refer to Table 2, Table 3 and Table 7 (pages 5, 9, and 13 

respectively) for a review of the Model 1835-C’s functions and capabilities. 

The following instructions assume familiarity with the meters functions. They 

also include steps to incorporate background correction and assume that the 

experimental setup underfills and does not saturate or damage the detector. 

2.8.1 Making DC Power Measurements 

The following process describes the procedure for making basic optical power 

measurements while properly removing the influence of ambient light and 

other drift effects. 

i. Plug in a Newport Low-Power or High-Power detector via its associated 

calibration module and then turn the meter on. Set MODE to DC CONT, set 

AUTO on and set the measurement wavelength to the desired value. 

ii. When using a Newport High-Power (thermopile) detector, execute AUTO 

CAL per Section 2.4.4. 

iii. Cover or otherwise block the source that you will be measuring and then 

turn ZERO on. 

iv. Uncover the source so that it illuminates the detector and note the display 

value. This reading is the optical power observed by the detector due to 

the source. 

The process as detailed assumes that the ambient signal is not changing 

between when you zero the display and when you make your measurement. 

Remember, if you can see your detector as you move around, then your 

detector can see you as a changing ambient DC signal! 

2.8.2 Making Peak-to-Peak Power Measurements 

The following process describes the procedure for making basic optical peakto-peak 

power measurements. 

i. Plug in a Newport Low-Power detector via its associated calibration 

module and then turn the meter on. Set MODE to P-P CONT, set AUTO on 

and set the measurement wavelength to the desired value. 

ii. Illuminate the detector and note the display value. This reading is the 

peak-to-peak optical power observed by the detector. 

23

2.8.3 Making Pulse Energy Measurements 

The following process describes the procedure for making basic optical pulse 

energy measurements. 

i. Plug in a Newport Energy detector via its associated calibration module 

and then turn the meter on. Set MODE to CONT PULSE, set AUTO on and 

also set the measurement wavelength to the desired value. 

ii. Illuminate the detector and note the display value as the meter measures 

each laser pulse. These readings represent the energies of the incident 

laser pulses. The meter will display the last pulse energy measured until a 

new pulse arrives. 

2.8.4 Making a Signal Integration Measurement 

The following process describes the procedure for making a basic signal 

integration measurement while properly removing influence of ambient light 

and other drift effects. The Model 1835-C begins and ends integration via the 

arrival of a trigger signal such as is received from the R/S key. 

i. Plug in a Newport Low-Power or High-Power detector via its associated 

calibration module and then turn the meter on. Set MODE to DC CONT, set 

AUTO on and also set the measurement wavelength to the desired value. 

ii. When using a Newport High-Power (thermopile) detector, execute AUTO 

CAL per Section 2.4.4. 

iii. Cover or otherwise block the source that you will be measuring, turn ZERO 

on and then set the MODE to INTG. As you enter the INTG mode, the 

meter will begin to acquire and integrate data. The display value may 

reflect the integration of noise due to ambient temperature fluctuations 

(thermopile) or light fluctuations (photodiode). 

iv. Uncover or trigger the source. The display value should now reflect 

detector signal integration process by continuously increasing. 

v. Press the R/S key to stop the integration and freeze the display value at the 

final integration value. 

NOTE 

The process as described above assumes that ambient signals are not 

changing between when you zero the display and when you make your 

measurement. 

2.8.5 Measuring a Laser Pulse Energy with a Thermopile Detector 

This application makes use of the Model 1835-C’s INTG mode. When an optical 

pulse with energy E(λ ) , is incident on a thermopile, a voltage signal arises as 

the heat pulse flows out to the cooling fins. The integrated signal resulting from 

this heat pulse is a measure of the optical pulse energy, Figure 8. 

24

Input Optical 

Pulse Energy, E (λ) 

E (λ) 

Resultant Voltage 

Pulse from Thermopile 

V (t) 

Integrate Voltage 

to find E (λ) 

E (λ) = 

1 

R (λ) 

∫ 

V (t) dt 

Figure 8. Measuring Laser Pulse Energy via a Thermopile in INTG Mode 

A recommended procedure is: 

i. Plug in a Newport High-Power detector via its associated calibration 

module and then turn the meter on. Set MODE to DC CONT, set AUTO on, 

set the measurement wavelength to the desired value and then execute 

AUTO CAL per Section 2.4.4. Now set ZERO on and then MODE to INTG. 

ii. Press the R/S key to begin the integration. Before the optical pulse arrives, 

the display may reflect the integral of detector noise due to ambient 

temperature fluctuations. 

iii. Trigger the laser pulse and watch the display increase at a much faster 

rate due to the detector signal from the heat flow. 

iv. When the display increase begins to slow down and again reflect integration 

of the detectors noise component, press the R/S key a second time to 

stop the integration. The final display value represents the pulse energy. 

NOTE 

If the integrated result of the pulse signal is much larger than the integral of 

the detector’s noise component, the display will show a steady reading after 

the pulse. If the integrated result of the pulse is not much larger, then error 

in the measurement will arise due to the uncertainty generated by integration 

of the noise component terms. 

NOTE 

The time constant of a thermopile detector determines the amount of time 

that one should expect to wait when making an integrated energy measurement 

of an optical pulse. Typically, an accurate value will be arrived at 5 

time constants after the arrival of the optical pulse. Newport High-Power 

detector time constants are listed in the Newport Catalog and in each 

detector’s manual. 

25

2.8.6 Using the Model 1835-C as an Exposure Controller 

This application uses the INTG measurement mode along with triggering 

features to configure the Model 1835-C as an exposure meter-controller. Use 

the following setup and procedure: 

i. Connect a BNC cable between the Model 1835-C’s trigger input and trigger 

output BNC connectors. Using a T-connector, connect the trigger output 

BNC to your shutter’s external control BNC. 

ii. Configure the trigger output to TRIG AT INTG and set the energy level at 

which you wish the exposure to stop, see Section 2.4.7. Adjust the polarity 

of the trigger output to open the shutter when the trigger output is active. 

iii. Set the meter to INTG mode with AUTO on and then press the R/S key to 

begin the integration and open the exposure controlling shutter. 

iv. The display value will increase until the INTG trigger output threshold is 

crossed. At the threshold, integration will stop and the trigger output will 

close the shutter. The display now shows the final integration value from 

the exposure. 

NOTE 

One can also configure the Model 1835-C as an exposure timer-controller by 

configuring the trigger output as TRIG AT FREQ and setting the trigger 

frequency appropriately. 

26

Section 3 

Principles of Operation 


The Model 1835-C’s electronics adapt to a number of signal measurement 

tasks: DC current or voltage, AC peak-to-peak current or pulse voltage, or 

integrated DC current or voltage signals. This versatility is required to handle 

the various signals that Newport’s Low-Power, High-Power and Energy 

detector families generate. These detector families are based on semiconductor, 

thermopile and pyroelectric detectors respectively. 

Detector data is introduced to the Model 1835-C by way of a calibration 

module specific to the detector in use. At power up (and RESET), the 1835-C 

uploads information about the detector from the calibration module which 

describes the set of operating states available to the detector. A user then 

selects among the available operating states when using the meter. Front 

panel control and the operating states of the Model 1835-C are discussed in 

Sections 2.3 and 2.4. 

3.2 Analog Signal Flow 

Detector signals can follow many different paths through the Model 1835-C 

input amplifier chain. A block diagram of analog signal flow is shown in 

Figure 9. The actual flow path depends upon the detector type and the 

mode of measurement. 

Input 

V 

I 

Prog. Voltage 

Amp. 

Prog. Bandwidth 

Noise Filter 

Voltage 

Buffers 

Analog 

Output 

Prog. Transimpedence 

Current Amp. 

+ 

– 

A/D 

A/D 

Peak 

Detector 

Peak - Peak & 

Peak - Baseline 

4,096 Cnt 20,000 Cnt 

Baseline 

Hold Circuit 

Figure 9. Model 1835-C Analog Signal Flow Diagram 

27

The analog signal flow path is primarily determined by the responsivity units 

of the detector. The numerator of these units indicates how the meter must 

be configured in order to obtain a calibrated optical measurement. Analog 

signal flow is independent of whether SNGL or CONT measurements are made. 

Responsivity units and signal flows for the various detector families is listed in 

Table 22. 

Table 22. Analog Signal Flow Paths. 

Detector Family Resp. Units Mode Amplifier Path Peak-Peak A/D Converter 

Low-Power A / W DC I No 20,000 or 4,096 

Low-Power A / W P-P I , AC coupled Yes 4,096 

Low-Power A / W INTG I No 4,096 

High-Power V / W DC V only No 20,000 or 4,096 

High-Power V / W INTG V only No 4,096 

Energy V / J PULSE V only Yes 4,096 

3.3 Digitized Signal Flow 

Signals that are captured by one of the analog-to-digital converters are further 

processed as illustrated in the signal flow block diagram of Figure 10. Raw 

signals are acquired by the analog-to-digital converters and have the units of 

current or voltage depending upon how the input amplifier chain was configured. 

These digitized signals move through a number of process steps which 

may or may not alter the digitized value depending upon the operating state of 

the meter. Each of these possible processing steps is discussed in their order 

of occurrence. 

Detector 

Calib. 

Module 

Figure 

9 

DIG 

Filter 

Gain 

ZERO 

Responsivity 

Map(s) 

ZERO 

Reference 

Front Panel 

UNITS 

STO-REF 

Reference 

Remote 

Interface 

VFD 

Display 

STATS 

Buffer 

Data Store 

Buffer 

Digital Filter 

Figure 10. Model 1835-C Digitized Signal Flow Block Diagram 

If the digital filter annunciator DIG is on, Section 2.3.4, the filter output is the 

average of the most recent 10 digitized values. When less than 10 values are 

have been acquired since the last reset of the digital filter, the output is the 

average of all the values received. The digital filter is reset when the Model 

1835-C is turned on, and whenever the UNITS or the range changes or when 

the MODE key is pressed. 

28

NOTE 

When using the digital filter in SNGL acquisition mode , each measurement is 

the average of the last 10 acquisitions independent of how old any of the 

measurements are. 

Gain 

Gain processing accounts for the signal gain of the input amplifiers. The 

output is the product of the digitized value and the amplifier gain. 

Zero Offset 

Zero offset is active whenever the ZERO annunciator is lit, Section 2.3.5. The 

zero offset output is equal to the input value less the zero reference value, 

S-S o 

. 

Responsivity Map(s) 

This process scales the input value in accordance with current calibration 

wavelength and the responsivity map downloaded from the detector calibration 

module. The output of this process, i.e. the measurement value, is the 

digitized input value divided by the responsivity associated with the current 

calibration wavelength or the user defined calibration value. Different 

responsivities are used depending upon if the attenuator, ATTN, annunciator 

is lit, Section 2.3.8. 

Units Correction 

Units correction adjusts a measurement value to account for the display units 

selected. When the display units are equal to the detector signal units, i.e. 

equal to the numerator of the responsivity units, Table 22, the measurement 

value is not adjusted. Otherwise the digitized value is adjusted to account for 

detector responsivity and/or additional unit conversions such as Joules-to- 

Ergs or W-to-W/cm 2 . 

NOTE 

Per area unit conversions such as W-to-W/cm 2 divide the measurement value 

by the active area of the detector. This calculation assumes that the entire 

active area of the detector is uniformly illuminated. Per area measurements 

where the entire detector active area is not uniformly lit are not accurate. 

The user must insure that these conditions are met before utilizing per area 

units. 

Data Store Buffer 

Units correction adjusts a measurement value to account for the display 

units selected. When the display units are equal to the detector signal units, 

i.e. equal to the numerator of the responsivity units, Table 22. 

29

P or E = S R λ 

3.4 Typical Detector Signals 

The flexibility of the Model 1835-C analog signal flow is required in order that 

it may properly measure the signals that various types of detectors make. 

Basic optical power or energy measurements are related to a measured 

detector signal, S, in the following way: 

Where: R λ 

= Detector responsivity at λ . 

S = Detector signal 

Semiconductor (Newport Low-Power) detectors, provide a current signal. 

The 1835-C is capable of 100 fA resolution in order to provide the highest 

sensitivity performance with these detectors. 

Thermopile (Newport High-Power) detectors, provide a small voltage signal. 

The 1835-C is capable of 125 nV resolution in order to reach the sensitivity 

limits of thermopile detectors. 

Pyroelectric (Newport Energy) detectors, deliver a peak voltage signal, 

S = V pk 

. The 1835-C is capable of capturing 2 µsec rise time voltage spikes so 

that it may operated with the fastest of these detectors. 

3.5 Thermopile Detector Signals 

Thermopile detectors respond with a voltage signal that slowly to changes in 

incident optical power. The time constant of most thermopile detectors is on 

the order of 1 to 10 seconds. 

Input Optical Signal 

Thermopile 

Response 

Displayed Signal 

1 sec 5 sec 

Figure 11. Thermopile Signals exhibit 1 to 10 second time constants. 

30

3.6 Pulse Energy Detector Signals 

A Newport Energy detector will respond to a single radiant energy pulse with 

a voltage pulse at its BNC output. This pulse exhibits a sharp voltage rise to a 

peak followed by a slower voltage decay which “undershoots” zero volts 

before settling back to zero volts. When a detector is operated within its 

proper limits, the voltage difference from immediately before the sharp rise to 

the peak is linearly proportional to the radiant energy. 

If a second pulse arrives before the “undershoot” rises back to zero volts, the 

voltage rise from this pulse will start from an initial negative value. At sufficient 

energy pulse repetition rates, a negative “baseline” voltage will develop from 

which the voltage rise must now be measured to achieve accurate energy 

readings. The 1835-C contains baseline capture circuitry which maintain its 

accuracy specifications over rep-rates ranging from single pulse to 2 kHz. 

1.0 

0.8 

VOLTS 

0.6 

0.4 

V peak 

0.2 

0.0 

0.00 0.02 0.04 0.06 0.08 0.10 

TIME (sec) 

Figure 12. Typical Newport Energy Detector Signal Waveform — An energy 

detector signal sharply rises to a peak value and then decays going somewhat 

negative before finally returning to zero. The energy in the radiant 

pulse is proportional to the height of the peak measured from immediately 

before the sharp rise. 

1.0 

0.8 

VOLTS 

0.6 

0.4 

V peak 

0.2 

0.0 

0.0 0.2 0.4 0.6 0.8 1.0 

TIME (sec) 

Figure 13. Negative Baseline Voltage Due to a Pulse Train — If a laser pulse 

arrives before the previous Energy detector signal has fully decayed, the 

detector signal rises from the present decay point of the previous signal. 

31

3.7 Peak-to-Peak (Photodiode) Detector Signals 

The Model 1835-C allows one to make peak-to-peak measurements of time 

varying signals from semiconductor photodiode detectors. Since optical 

power is a zero bounded positive quantity, signals from a detector observing 

such modulated light will similarly be zero bounded positive signals. To make 

a peak-to-peak measurement, the Model 1835-C must be able to capture both 

the maximum and minimum values of a detector signal. This is accomplished 

by AC coupling the incoming detector signal so that the original minimum 

value shows up as a negative peak. 

DC Average 

AC Peak-to-Peak 

DC + AC Peak 

Figure 14. Time Varying Signal Measurements — Many different measurements 

can be made on different portions of a time varying signal. The most 

common are: DC power, peak power, and peak-to-peak power. 

The Model 1835-C can only measure periodic AC peak-to-peak signals within 

the frequency range: 50 – 7,000 Hz. Above 7,000 Hz, bandwidth limitations 

significantly effect the accuracy of the peak-to-peak measurement. Below 50 

Hz, the AC coupling attenuates signals and measurement accuracy. However, 

low frequency measurements can be quantified in DC CONT measurement 

mode, see note below. 

NOTE 

Peak-to-peak measurements of frequencies below 50 Hz can be accomplished 

by observing the MAX-MIN value of the STATS buffer in DC CONT measurement 

mode, Sections 2.3.12 and 2.3.14. To do so, disable the analog filter, 

adjust the sample rate, Section 2.4.6 and the STATS buffer depth, Section 

2.3.14, so that the actual maximum and minimum values will be captured by 

the stream of DC measurements. 

32

3.8 Integration of Detector Signals 

The Model 1835-C provides for making measurements that integrate incoming 

power detector signals to obtain an energy via the INTG mode, Section 2.3.12. 

In INTG mode, the display units indicate Joules since energy is the time 

integral of power: 

t1 

E λ P λ dt 

t0 

t1 

( )= ∫ ( ) = ∫ 

t0 

() 

( ) 

St 

R λ 

As the detector signal actually consists of a stream of digitized values, the 

integral becomes a numerical approximation using the trapezoid method, 

Figure 15. In order to maintain the highest accuracy for this numerical 

process, the sample rate is set at its maximum value of 500 Hz. 

dt 

Detector Signal 

Numerical Integration 

Trapezoid Method 

Magnitude of the 

Integraged Result 

Figure 15. Integrated Energy Via a Trapezoid Approximation — The INTG 

measurement mode performs a discrete integration at a 500 Hz sample rate. 

Two common applications are natural extensions of the INTG measurement 

mode: 

1. Pulse laser energy measurement using with a thermopile detector, 

Section 3.5 

2. Energy from exposure over a period of time (dosage), Section 3.6. 

33

Input Optical 

Pulse Energy, E (λ) 

E (λ) 

Detector's Voltage 

Pulse 

V (t) 

Integrate Voltage 

to find E (λ) 

E (λ) = 

1 

R (λ) 

∫ 

V (t) dt 

Figure 16. Measuring Laser Pulse Energy with a Thermopile — Thermopiles 

are often used to measure pulsed laser energy by integrating the response of 

the detector to the pulse. 

3.9 Analog Output 

The Model 1835-C provides a 0 to 2.5 volt, into 50Ω, BNC analog output for 

signal monitoring. The analog output is the actual amplified detector signal 

and is uncorrected for the effects of the detector’s responsivity, AUTO CAL, 

and ZERO. 

3.10 Measurement Considerations 

This section describes detector characteristics, optical and electrical considerations, 

and environmental influences on optical measurements. In general, 

measurement accuracy is limited by the calibration accuracy of the detector 

calibration. Accurate measurements however, are also dependent upon 

proper set-up, controlling temperature and illumination conditions and 

understanding the factors that affect optical measurements. 

3.10.1 Detector Calibration and Accuracy 

Newport Corporation calibrates its detectors using secondary standards 

directly traceable to the United States National Institute of Science and 

Technology (NIST) or to Great Britain’s National Physical Laboratory, (NPL). 

The details and accuracy of the calibration procedure vary with each detector 

model but a detailed description of the calibration results is supplied with 

each individually calibrated detector. 

In general, detector calibration accuracy varies from 2% to 5% in absolute 

terms and varies with wavelength. Each detector will also have some variation 

in response over its surface. Therefore, for the most reproducible measurements, 

light should illuminate the detector as uniformly as possible over 

as large an area as practical. 

CAUTION 

Avoid focusing a light source onto the detector surface. Inaccurate 

readings and possible detector damage may result. Consult the detector 

manual for saturation or damage thresholds. 

34

NIST traceability requires that detectors be recalibrated on one year intervals. 

As individual detector responses change with time, especially in the ultraviolet, 

recalibration is necessary to assure confidence in the accuracy of the 

measurement. For the most reproducible measurements, the same detector 

should always be used for measurements which are to be directly compared. 

3.10.2 Quantum Detector Temperature Effects 

Semiconductor, Newport Low-Power detectors, are affected by temperature. 

At long wavelengths, quantum detectors typically lose sensitivity with increasing 

temperature. Additionally, detector dark current increases exponentially 

with temperature. 

Observed dark current is often dominated by the interaction between the 

detector and a meter’s amplifier and is typically larger than the theoretical 

dark current limit. Silicon detectors are inherently quieter than germanium 

detectors due to their higher internal resistance and lower capacitance. The 

noise or drift in the dark current sets a lower bound on the measurement 

resolution which can be achieved with any given detector. Cooling a detector 

significantly lowers its dark current and dark current noise. 

The observed dark currents can also be zeroed at any moment via the ZERO 

function. Since dark currents drift with temperature, the ZERO should be 

adjusted just prior to taking any measurements. If the detector temperature is 

constant, sensitivity changes and dark current drifts are significantly reduced. 

3.10.3 Thermopile Detector Temperature Effects 

Thermopile, Newport High-Power detectors, are significantly affected by 

temperature fluctuations arising from air flow disturbances. As the detector is 

a temperature measuring device, air flow disturbances set a practical lower 

limit on the power that a detector can measure. In order to get the most out 

of any thermopile detector, be careful to shield the detector from air flow 

disturbances. Common sources of disturbance are: air conditioners and 

people walking past. 

3.10.4 Energy Detector Temperature Effects 

Pyroelectric, Newport Energy detectors, are AC coupled devices and thus are 

not susceptible to temperature induced DC signal offsets or noise floor 

changes. One generally does not need to take much precaution with pyroelectric 

detectors except to make sure that their damage threshold is not exceeded. 

3.10.5 Ambient and Stray Light 

Ambient and stray light striking the detector should be considered when 

making a measurement. Ambient light can be distinguished from dark current 

(or the detector/meter noise floor) by either turning off or blocking the source 

and covering the detector face with opaque material such as a piece of black 

rubber. 

Using the human hand to cover the detector is not advised because it emits a 

significant amount of infrared radiation and radiates a temperature significantly 

different from ambient. With the detector covered, a reading of the 

dark current may be made. Next, remove the material which is covering the 

detector and take another reading. The difference is the ambient light level. 

35

NOTE 

Changes in ambient light levels can occur from such factors as turning room 

lights on or off, or by moving people or equipment. Remember, if you can 

see your detector element, then your detector can see the light bouncing off 

you. 

The effects of ambient light are greatly reduced when using a fiberconnectorized 

signal input to the detector. If free-space beam measurements 

are desired, using an attenuator will often improve the signal to ambient signal 

noise level. Wavelength-specific filters, such as optical cutoff, bandpass, or 

spike filters can be used if the signal wavelength spectrum permits. Other 

techniques to reduce stray light include using apertures, placing the detector 

in a box or other housing to shield the surface from light (or air currents) and 

turning off room and other polluting light sources. 

3.10.6 Common Measurement Errors 

The most common sources of optical measurement error are listed in Table 23 

below. Other common errors are discussed in the preceding subsections of 

Section 3.10 Measurement Consideration. 

Type of Error 

Radiometry 

Ambient Light 

Wavelength Calibration 

Detector Saturation 

or Damage 

Table 23. Common Measurement Errors 

What should be done? 

Check that all of the light is actually hitting the 

detector. 

Check that any ambient light was ZEROed before 

the measurement was made. 

Check that the Calibration Factor for the measurement 

wavelength is properly set. 

Check that the optical power density remains 

below the detector’s saturation or damage 

threshold. 

NOTE 

The Model 1835-C will indicate when a detector is being operated above its 

saturation or damage threshold by displaying “SA” in the measurement 

display area. Be aware that detectors often experience local saturation or 

damage without ever exceeding an overall saturation or damage threshold. 

This only applies to semiconductor photodiodes and thermopiles used 

above maximum intermittent power. 

Detector damage can still arise even when “SA” is not displayed. Be sure to 

follow your detector manual’s user guidelines. 

36

Section 4 

Computer Interfacing 

4.1 General Guidelines 

The 1835-C has two computer interface ports: GPIB and RS-232C. The GPIB 

port conforms with the IEEE Standard 488.1 hardware standard and the IEEE 

488.2 software standard. The protocol for the RS-232C port conforms as much 

as possible to the IEEE 488.2 software standard. 

As specified by the IEEE 488.2 standard, there are two command types; device 

independent commands and device dependent commands. The device 

independent commands have the same meaning to all devices and are defined 

as part of the IEEE 488.2 standard. All device independent commands start 

with an asterisk ( ). Device dependent commands do not start with an 

asterisk and have 

* 

meanings unique to the Model 1835-C. 

A query is a command that invokes a response from the meter. All queries are 

terminated by a question mark (?). It is recommended that when a query is 

made, that the response to that query be read before other commands are 

issued. When a query is made to the GPIB interface, the MAV bit in the status 

byte should be checked by means of a serial poll to make sure that the data is 

available before the reading the response. (See Appendix C.4 Status Byte) 

4.2 Computer Interface Terminology 

Listed below are key abbreviations and concepts used in the command 

reference section of this manual. 

Delimiting Punctuation 

For the purposes of this manual, any string enclosed by is considered to 

be a command, a string or a numerical argument. The punctuation is 

used to symbolize the typographic limits of the command, string or argument 

in question. 

End or Identify 

An IEEE 488.1 signal sometimes sent with the end-of-string character. 

Individual Status 

This status is generated by the status byte and parallel poll enable register. It 

is used in responding to parallel polls. 

37

Carriage Return 

The ASCII encoded byte 13 in decimal. (0D hex) 

Line Feed 

The ASCII encoded byte 10 in decimal. (0A hex) 

New Line 

Defined in the IEEE 488.2 standard as the ASCII encoded byte 10 in decimal. 

(0A hex) 

End of Message 

Indicates the concurrent transmission of with the a data byte. 

(;) Semicolons 

Used to separate commands within a single transmission (concatenation). 

Numerical Types 

Numerical parameters are passed and returned as the actual ASCII characters 

in the string representation of the number. See the appendix for a detailed 

description of . 

String Types 

See the appendix for a detailed description of 

RS-232C Command Termination 

When a command is received from the RS-232C port, either a or a is 

treated as the command terminator. 

GPIB Command Termination 

When a command is received from the GPIB port, either an with a data 

byte, , or is treated as the command terminator. The recommended 

form of termination is an sent with a denoted as in 

this manual. 

RS-232C Response Termination 

In RS-232C echo mode responses are terminated by a sequence. In 

RS-232C normal mode the character terminates the response. 

GPIB Response Termination 

All responses from the 1835-C GPIB port are terminated by an sequence. 

Which is the concurrent transmission of with a data byte. 

38

4.3 Entering Remote Computer Interface Mode 

When a command or query is received by the GPIB or RS-232 interface ports, 

the 1835-C automatically goes into remote interface mode. The message area 

on the display will indicate which remote port received the command. 

While in remote mode, the keypad is disabled except for the power and 

key. To get out of remote mode press the key. If the 

1835-C is in local lockout then the LLO remote command must be used to 

disable local lockout before you will be able to return to keypad control. The 

message area of the display will indicate when the keypad is in local lock out 

state. 

4.4 RS-232C Communication 

Before communicating with the 1835-C through the RS-232 port, proper cable 

connections must be made. Figure 16 shows the cable connections for 

communicating with the RS-232C port on the 1835-C. 

Once cable connections are made, the baud rate and echo mode need to be 

set. Valid baud rates are 19.2K, 9600, 4800, 2400, and 1200. The parity, data 

bits, and stop bits are fixed at no parity, 8 data bits, and 1 stop bit. 

RS-232C Parameters 

Baud Rate 19.2K, 9600, 4800, 2400, or 1200 

Parity 

none 

Data bits 8 

Stop bits 1 

When the echo mode is enabled the 1835-C generates a ‘> ‘ prompt for every 

new line and all characters sent to the 1835-C are echoed back over the 

interface. Error messages are reported over the interface immediately. As the 

user is entering commands the line may be edited by using the backspace key 

(sending an ASCII decimal 08 code) or by using the DEL key (sending an ASCII 

decimal 127 code). 

In echo mode the RS-232C port is interactive and especially useful when a 

dumb terminal type of device is used to communicate with the 1835-C. 

When echo mode is disabled (normal mode) the 1835-C does not generate a 

prompt or echo characters back over the interface. Error messages must be 

accessed by using the *ERR? query. This is the default state of the echo 

mode. 

39

TO 1835 

CABLE TERMINATORS (RS-232) 

9 pin to 25 pin 

TO COMPUTER 

9 PIN 

PIN NO. 

CODE 

DESCRIPTION 

25 PIN 

PIN NO. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

DCD 

RXD 

TXD 

DTR 

GND 

DSR 

RTS 

CTS 

RI 

CARRIER DETECT 

RECEIVE DATA 

TRANSMIT DATA 

DATA TERM. READY 

SIGNAL GROUND 

DATA SET READY 

REQUEST TO SEND 

CLEAR TO SEND 

RING IND. 

8 

3 

2 

20 

7 

6 

4 

5 

22 

TO 1835 

CABLE TERMINATORS (RS-232) 

9 pin to 9 pin 

TO COMPUTER 

9 PIN 

PIN NO. 

CODE 

DESCRIPTION 

9 PIN 

PIN NO. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

DCD 

RXD 

TXD 

DTR 

GND 

DSR 

RTS 

CTS 

RI 

CARRIER DETECT 

RECEIVE DATA 

TRANSMIT DATA 

DATA TERM. READY 

SIGNAL GROUND 

DATA SET READY 

REQUEST TO SEND 

CLEAR TO SEND 

RING IND. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

Figure 17. RS-232 Cable Connections 

4.4.1 Setting Baud Rate and Echo Mode From The Keypad 

The baud rate and echo mode are set from within the menu structure. To set 

the baud rate select the BAUD RATE option from the REMOTE SETUP menu. 

To set the echo mode select the ECHO MODE option from the REMOTE SETUP 

menu. (See Section 2.4.12) 

4.4.2 Setting Baud Rate and Echo Mode From A Remote Interface 

The baud rate cannot be set from the remote interface. To set the echo mode 

use the ECHO command. Use the ECHO? to see if the echo mode is enabled or 

disabled. (See Section 2.4.12) 

40

4.5 RS-232C XON/XOFF Handshaking Protocol 

The 1835-C uses the XON/XOFF handshaking protocol. When the 1835-C’s RS- 

232 input buffer is nearly full the 1835-C will send an XOFF (ASCII encoded 19 

decimal) character to the remote computer. The XOFF character informs the 

remote computer that it needs to suspend transmission until it receives the 

XON character from the 1835-C. When the buffer empties sufficiently the 1835- 

C will send an XON (ASCII encoded 17 decimal) to signal the remote computer 

that it can resume transmission. 

The 1835-C will also respond to XOFF and XON characters sent to it from the 

remote computer. When the 1835-C receives an XOFF character it will suspend 

all transmission of characters to the remote computer until the XON 

character is received. 

4.6 GPIB Communication 

A variety of third party GPIB communication hardware and software, such as 

plug-in GPIB computer boards and Lab View software from National Instruments 

exists. The 1835-C should work with any of these as long as they 

adhere to the IEEE 488.1 standard. This manual assumes the user is familiar 

with one of these third party hardware/software packages. The table below 

summarizes the IEEE 488.1 capabilities supported by the 1835-C. 

Table 24. Model 1835-C IEEE 488.1 Capabilities Summary 

Description Command Level of Capability 

Source Handshake SH1 complete capability 

Acceptor Handshake AH1 

complete capability 

Talker T6 basic talker, serial poll, unaddress if 

MLA 

Extended Talker TE0 no capability 

Listener L4 basic listener, unaddress if MTA 

Extended Listener LE0 no capability 

Service Request SR1 complete capability 

Remote Local RL0 *no capability 

Parallel Poll PP1 remote configuration 

Device Clear DC1 complete capability 

Device Trigger DT0 no capability 

Controller C0 no capability 

NOTE 

* In order to better handle the RS-232C interface the 1835-C automatically 

goes into remote mode when a command is received from either of the 

remote computer interfaces. The LLO command is used to enable or disable 

the local lockout state. 

41

4.6.1 Setting The GPIB Address 

Before communicating with the 1835-C GPIB port the 1835-C GPIB address 

must be set. The address can be between 0 and 30. The address can only be 

set from the keypad and is accessed through the menu structure. To set the 

GPIB address select the REMOTE SETUP->GPIB ADDRESS option in the menu. 

The Model 1835-C GPIB is factory set to 5. (See Section 2.4.12) 

42

Section 5 

Command Reference 

5.1 Model 1835-C Remote Interface Commands 

The Model 1835-C remote commands can be divided into two groupings: 

i. Device Independent Commands, Section 5.2 

ii. Device Dependent Commands., Section 5.3 

Table 25 lists the Device Independent Commands supported by the 1835-C 

while Table 26 lists the Device Dependent Commands supported the 1835-C. 

Following these tables are the detailed presentations of each command and 

their syntax and an example of their use. 

Command 

*CAL? 

*CLS 

*ERR? 

*ESE 

*ESE? 

*ESR? 

*IDN? 

*IST? 

*OPC 

*OPC? 

*PRE 

*PRE? 

*RCL 

*RST 

*SAV 

*SRE 

*SRE? 

*STB? 

*TST? 

*WAI 

Table 25. Device Independent Status Commands 

Command Name 

Calibration Query 

Clear Status 

Error Query 

Event Status Enable 

Event Status Enable Query 

Event Status Register Query 

Identification Query 

Individual Status Query 

Signal When Operation Complete 

Operation Complete Query 

Parallel Poll Enable 

Parallel Poll Enable Query 

Recall Device Configuration 

Software Reset 

Save Device Configuration 

Service Request Enable 

Service Request Enable Query 

Status Byte 

System Test 

Wait To Continue 

43

Table 26. Device Dependent Commands 

Command Command Name 

ATTN 

Attenuator Calibration Data Enable 

ATTN? 

Attenuator Calibration Data Enable Query 

ATTNSN? Attenuator Serial Number Query 

AUTO 

Auto Ranging Enable 

AUTO? 

Auto Ranging Enable Query 

BARGRAPH Bar Graph Enable 

BARGRAPH? Bar Graph Enable Query 

CALDATE? Calibration Date Query 

DETMODEL? Detector Mode Query 

DETSN? 

Detector Serial Number Query 

DETSW 

Detector Switch Select 

DETSW? Detector Switch Query 

DISP 

Display Brightness Select 

DISP? 

Display Brightness Query 

DS? 

Data Store Value Query 

DSBUF 

Data Store Buffer Behavior Select 

DSBUF? 

Data Store Buffer Behavior Query 

DSCLR 

Data Store Clear 

DSCNT? 

Data Store Value Count Query 

DSE 

Data Store Enable 

DSE? 

Data Store Enable Query 

DSSIZE 

Data Store Buffer Size Select 

DSSIZE? 

Data Store Buffer Size Query 

DSUNITS? Data Store Units Query 

ECHO 

RS-232 Echo Mode Enable 

ECHO? 

RS-232 Echo Mode Enable Query 

EVENT? 

Device Event Register Query 

EVENTEN Device Event Enable Register 

EVENTEN? Device Event Enable Register Query 

EXT 

External Trigger Enable 

EXT? 

External Trigger Enable Query 

EXTEDGE External Trigger Edge Select 

EXTEDGE? External Trigger Edge Query 

FILTER 

Filter Select 

FILTER? Filter Query 

LAMBDA Lambda Select 

LAMBDA? Lambda Query 

LLO 

Local Lockout Enable 

LLO? 

Local Lockout Enable Query 

MODE 

Acquisition Mode Select 

MODE? 

Acquisition Mode Query 

R? Read Measurement Query 

RANGE 

Manual Range Level Select 

RANGE? Manual Range Level Query 

REFVAL 

Reference Value Select 

REFVAL? Reference Value Query 

RESP? 

Responsivity Query 

RUN 

Start Acquisition 

RWS? 

Read Measurement with Status Query 

SFREQ 

DC Sample Frequency Select 

SFREQ? 

DC Sample Frequency Query 

SPREC 

DC Sample Type Select 

SPREC? 

DC Sample Type Query 

STMAX? Statistics Buffer Maximum Value Query 

44

STMEAN? 

STMIN? 

STMXMN? 

STSDEV? 

STSIZE 

STSIZE? 

STOP 

STOREF 

STOZERO 

TONE 

TONE? 

TRIGOUT 

TRIGOUT? 

TRIGOUTFREQ 

TRIGOUTFREQ? 

TRIGOUTINTG 

TRIGOUTINTG? 

TRIGOUTLVL 

TRIGOUTLVL? 

TRIGOUTPOL 

TRIGOUTPOL? 

UNITS 

UNITS? 

USRCAL 

USRCAL? 

USRRESP 

USRRESP? 

ZERO 

ZERO? 

ZEROVAL? 

Statistics Buffer Mean Value Query 

Statistics Buffer Minimum Value Query 

Statistics Buffer Maximum-Minimum Value Query 

Statistics Buffer Standard Deviation Query 

Statistics Buffer Size Select 

Statistics Buffer Size Query 

Stop Acquisition 

Store Reference Reading 

Store Zero Signal 

Tone Enable 

Tone Enable Query 

Trigger Out Mode Select 

Trigger Out Mode Query 

Trigger Out Frequency Select 

Trigger Out Frequency Query 

Trigger Out Integration Level Select 

Trigger Out Integration Level Query 

Trigger Out Level Select 

Trigger Out Level Query 

Trigger Out Polarity Select 

Trigger Out Polarity Query 

Units Select 

Units Query 

User Calibration Enable 

User Calibration Enable Query 

User Responsivity Factor Select 

User Responsivity Factor Query 

Signal Zeroing Enable 

Signal Zeroing Enable Query 

Zero Signal Query 

5.2 Device Independent Commands 

*CAL? 

Calibration Query 

Syntax: *CAL? 

Parameters: None 

Function: 

This routing performs an auto calibration sequence that measures the amplifier 

offsets at all gain settings. These measurements are stored and subtracted 

from subsequent measurements. Acquisition is suspended during 

auto calibration and no other remote commands will be processed until the 

auto calibration sequence is complete. 

Returns: 

represents the integer 0. This return value is generated when 

autocalibration is complete. 

Related Commands: None 

45

*CLS 

Clear Status 

Syntax: *CLS 


Function: 

This command clears the Standard Event Status register, device event register, 

and the error queue. As a result of this command the status byte is 

cleared except for the message available bit (bit 4). Because this command 

does not clear the input and output buffers the MAV bit will not be affected. 

The *CLS command also cancels any outstanding *OPC and OPC? commands. 

Related Commands: *ESR?, EVENT?, *IST?, *STB? 

*ERR? 

Error Query 

Syntax: *ERR? 


Function: 

Returns (and removes) oldest error message from the error queue. The error 

message is made up of an error code and a text description of the error (see 

the appendix B). A maximum of 10 errors can be stored in the queue. If no 

errors are stored in the queue, a message to that effect will be returned. 

Errors that occur due to commands and queries sent from the RS-232 interface 

will be stored in the queue only if the echo mode is disabled. When the 

echo mode is enabled the error messages are automatically returned to the 

user when the error occurs. See Appendix B for a description of the error 

messages. 

The command *CLS will clear the error queue. 

Returns: , 

is of type and represents a negative integer error code. 

is of type in double quote format, and describes the 

error. See the appendix for a list of possible error messages. 

Related Commands: *CLS, *STB? 

*ESE 

Event Status Enable 

Syntax: *ESE 

Parameters: 

is an integer in the range 0 to 255 inclusive. is written to the 

Event Status Enable register. 

Function: 

The Event Status Enable register is AND’ed with the Event Status register. If 

any bit is set in the result of this AND’ing operation the ESB bit (bit 5) of the 

Status Byte will be set. The Status Byte can be used in conjunction with the 

Service Request Enable register to generate a service request. 

46

The Event Status Enable register is an 8 bit, bit mapped register. Any bit set to 

1 in the Event Status Enable Register allows the corresponding bit in the Event 

Status Register to set the ESB bit (bit 5) in the Status Byte. Any bit set to 0 

disables the corresponding bit in the Event Status Register from setting the 

ESB bit. The Event Status Enable register is set to 0 upon power-up. See 

Appendix C for a detailed description of the Event Status Register. 

The significance of each bit in the Event Status Enable register is shown 

below: 

7 

6 

5 

4 

3 

2 

1 

0 

Operation Complete Mask 

Request Control Mask (Not Used) 

Query Error Mask 

Device Error Mask 

Execution Error Mask 

Command Error Mask 

User Request Mask (Not Used) 

Power On Mask (Not Used) 

Event Status Enable Register 

Related Commands: *CLS, *ESE?, *ESR?, EVENT?, EVENTEN, EVENTEN?, *IST?, 

*PRE, *PRE?, *SRE, *SRE?, *STB? 

*ESE? 

Event Status Enable Query 

Syntax: *ESE? 


Function: 

This query returns the contents of the Event Status Enable register. See the 

*ESE command for a description of the Event Status Enable register. See 


Returns: 

is of type and represents an unsigned integer in the range 0 

to 255. 

Related Commands: *CLS, *ESE, *ESR?, EVENT?, EVENTEN, EVENTEN?, 

*IST?, *PRE, *PRE?, *SRE, *SRE?, *STB? 

*ESR? 

Event Status Register Query 

Syntax: *ESR? 


Function: 

This query returns the contents of the Event Status Register and clears the 

Event Status Register except for bit 3. bit 3 is determined by the state of the 

Device Event and Device Event Enable registers. The *CLS command will also 

set this register to 0. 

47

The Event Status register is AND’ed with the Event Status Enable register. If 

any bit is set in the result of this AND’ing operation the ESB bit (bit 5) of the 

Status Byte will be set. The Status Byte can be used in conjunction with the 

Service Request Enable register to generate a service request. See Appendix C 

for a detailed explanation of the Event Status Register. 

The Event Status Register is an 8 bit, bit mapped register, with each bit 

signifying a different condition. The bits are listed below, most significant bit 

first: 

7 

6 

5 

4 

3 

2 

1 

0 

Operation Complete 

Request Control (Not Used) 

Query Error 

Device Error 

Execution Error 

Command Error 

User Request (Not Used) 

Power On (Not Used) 

Standard Event Status Register 

Returns: 


to 255. 

Related Commands: *CLS, *ESE, *ESE?, EVENT, EVENTEN, EVENTEN?, *IST?, 

*PRE, *PRE?, *SRE, *SRE?, *STB? 

*IDN? 

Identification Query 

Syntax: *IDN? 


Function: 

This query causes the 1835-C to return device identification information. The 

information returned is manufacturer, model, serial number, and firmware 

version. 

Returns: ,,, 

is of type using the no quotes format. The 1835-C 

always returns Newport Corp.. 

is of type using the no quotes format. 

is of type using the no quotes format. This is always a ‘0’. 

is of type using the no quotes format. This text identifies 

the internal firmware version of the 1835-C. This text consists of two sections, 

separated by two underscores. The first section is the revision level, and the 

second is the revision date. 


48

*IST? 

Individual Status Query 

Syntax: *IST? 


Function: 

This query returns the current state of the IEEE 488.1 local message. 

The message is generated by the parallel poll status system. If any bit is 

set in the Status Byte and it’s corresponding bit is set in the Parallel Poll 

Enable register, then the message is set true (a value of 1). Otherwise 

the message is set false (a value of 0). 

When a parallel poll is conducted with the 1835-C configured to respond to it, 

the message is compared to the (sense bit). If they are the same 

then the configured data line will be driven true in response to the parallel 

poll. 

Both the and the data line driven during a parallel poll can be selected 

by the IEEE 488.1 parallel poll remote configuration command. 

Returns: 

is of type which represents the integer 0 or 1. 

Related Commands: *PRE, *PRE?, *STB? 

*OPC 

Signal When Operation Complete 

Syntax: *OPC 


Function: 

This command provides a means of synchronizing operations between the 

1835-C and the host. This command sets the Operation Complete bit (bit 0) of 

the Event Status register to 1 when all pending operations have completed. 

This bit will remain 1 until cleared by the *CLS command or the *ESR? query. 

This command can be used in conjunction with the *ESE and *SRE commands 

to cause a Service Request on the GPIB bus when all pending operations are 

complete. 

Once the *OPC command is received, it will not set the operation complete bit 

to 1 while any of the following operations are in progress: 

Single acquisition in progress 

Data store enabled with fixed data store buffer 

The meter is ranging 

Related Commands: *ESE, *ESE?, *ESR?, *OPC?, *SRE, *SRE?, *STB?, *WAI 

*OPC? 

Operation Complete Query 

Syntax: *OPC? 


49

Function: 

This query provides a means of synchronizing operations between the 1835-C 

and the host. This command generates a response when all pending operations 

have completed. 

When all pending operations are complete, this query will cause the Message 

Available bit (bit 4) of the Status Byte to be set because of the response 

generated. By enabling bit 4 of the Service Request Enable register (see *SRE), 

the *OPC? query can be used to cause a Service Request on the GPIB bus 

when all pending operations are complete. 

Once the *OPC? query is received, the response will not be generated while 

any of the following operations are in progress: 


Data store enabled with fixed data store buffer 


The *CLS or *RST commands, as well as a GPIB interface device clear, will 

cancel the operation complete query. 

Returns: 1 

The response is generated when all pending operations are complete. 

Related Commands: *OPC, *SRE, *SRE?, *STB?, *WAI 

*PRE 

Parallel Poll Enable 

Syntax: *PRE 

Parameters: 

is an integer in the range 0 to 255 inclusive. The value of this number 

is written into the Parallel Poll Enable register. 

Function: 

This command sets the Parallel Poll Enable register bits. The Parallel Poll 

Enable register is used in conjunction with the Status Byte to generate the IST 

(Individual Status) message. See Appendix C for a detailed description of the 

Event Status Register. 

The Parallel Poll Enable Register is set to 0 at power-on. 

The Parallel Poll Enable Register is an 8-bit, bit mapped register, with each bit 

signifying a different condition. The bits and their significance are detailed 

below: 

7 

6 

5 

4 

3 

2 

1 

0 

New Data Available 

New Valid Data Available 

Not Used 

Not Used 

Message Available Mask 

Event Status Byte Mask 

Master Summary Status Mask 

Error Queue Mask 

Parallel Poll Enable Register 

Related Commands: *IST, *PRE?, *STB? 

50

*PRE? 

Parallel Poll Enable Query 

Syntax: *PRE? 


Function: 

This query returns the contents of the Parallel Poll Enable register. See the 

*PRE command for a description of the Parallel Poll Enable register. See 


Returns: 


to 255. 

Related Commands: *IST, *PRE, *STB? 

*RCL 

Recall Meter Configuration 

Syntax: *RCL 

Parameters: 

is of type which rounds to an integer in the range 0 to 9. 

This number specifies a configuration storage buffer. The number 0 stands for 

the default configuration buffer. 

Function: 

This command configures the meter to a configuration previously stored in 

non-volatile memory (see *SAV), or to the default configuration for the 

attached detector. 

This command will fail if the requested configuration is incompatible with the 

detector attached to the meter or empty. The parameters affected by this 

command are those listed in Table 9. 

Returns: None 

Related Commands: *RST, *SAV 

*RST 

Reset 

Syntax: *RST 


Function: 

This sets the meter to the default configuration, see Table 9, for the detector 

attached to it. It also cancels any outstanding *OPC or *OPC? commands. 

Related Commands: *RCL, *SAV 

51

*SAV 

Save Meter Configuration 

Syntax: *SAV 

Parameters: 

is of type which rounds to an integer in the range 1 to 9. 

This number specifies a configuration storage buffer. 

Function: 

This command saves the configuration of the meter to the configuration 

specified by the parameter. The parameters saved by this command are 

those listed in Table 9. 

Related Commands: *RCL, *RST 

*SRE 

Service Request Enable 

Syntax: *SRE 

Parameters: 


is written into the Service Request Enable register. 

Function: 

The Service Request Enabled Register is used in conjunction with the Status 

Byte to generate service requests on the GPIB bus. See Appendix C for a 

detailed description of the Event Status Register. 

If a bit is set in the Service Request Enable register and it’s corresponding bit 

is set in the Status Byte Register, then a service request will be generated once 

for the for the given event. When service is being requested, bit 6 is set in the 

byte returned by a serial poll of the 1835-C. 

The Service Request Enable Register is an 8-bit, bit mapped register, with each 

bit signifying a different condition. The bits are listed below, most significant 

bit first: 

7 

6 

5 

4 

3 

2 

1 

0 



Not Used 

Not Used 

Message Available Mask 

Event Status Byte Mask 

Always Zero 

Error Queue Mask 

Service Request Enable Register 

Related Commands: *SRE?, *STB? 

52

*SRE? 

Service Request Enable Query 

Syntax: *SRE? 


Function: 

This query returns the contents of the Service Request Enable register. See 

the *SRE command for a description of the Service Request Enabled register. 

See Appendix C for a detailed description of the Event Status Register. 

Returns: 

is an integer in the range 0 to 255 inclusive, except that bit 6 is always 

a zero. 

Related Commands: *SRE, *STB? 

*STB? 

Status Byte Query 

Syntax: *STB? 


Function: 

This query returns the contents of the Status Byte which records current 

system conditions. Appendix C describes the Status Byte in detail. 

If a bit is set in the Status Byte Register and it’s corresponding bit is set in the 

Service Request Enable Register, then a service request will be generated once 

for the given event. When service is being requested, bit 6 is set in the byte 

returned by a serial poll of the 1835-C. 

The Status Byte Register is an 8-bit, bit mapped register, with each bit signifying 

a different condition. When a bit is set, or has a value of one, then the 

condition is true. The bits are listed below, most significant bit first: 

7 

6 

5 

4 

3 

2 

1 

0 



Not Used 

Not Used 

Message Available Bit 

Event Status Byte Bit 

Master Status Summary Bit 

Error Queue Bit 

Status Byte Register. 

Note that the *CLS common command clears most of the bits in the Status 

Byte. 

Returns: 

is an integer in the range 0 to 255 inclusive. 

Related Commands: *CLS, *SRE, *SRE? 

53

*TST? 

Self Test Query 

Syntax: *TST? 


Function: 

As defined in the IEEE 488.2 standard, the *TST? command causes the device 

to return a result of a self-test, indicating whether or not the unit completed 

the self-test without any errors. The self test is only administered upon reset 

or power up. The query does not initiate the self test and only returns a 0 

indicating that the system passed its earlier self test. 

Returns: 0 


*WAI 

Wait to continue 

Syntax: *WAI 


Function: 

The *WAI command causes the device to wait until all pending operations are 

complete before processing any commands waiting in the input queue. Care 

should be taken when using this command since it is possible to overflow the 

input queue by continuing to write commands to the 1835-C while the *WAI 

command is in effect. 

Note that the *WAI command will essentially “lock out” the remote interfaces 

until all pending operations are complete. The *OPC command and *OPC? 

query differ from *WAI in this area, as they allow other commands to be 

processed while they are waiting for pending operations to complete. 

Once the *WAI command is received, it will be in effect while any of the 

following operations are in progress: 


Data store in progress with fixed data store buffer 


The *WAI command can only be canceled by a GPIB interface device clear or 

by turning the meter off and on. 

Related Commands: *OPC, *OPC? 

5.3 Device Dependent Commands 

ATTN 

Attenuator Calibration Data Enable 

Syntax: ATTN 

Parameters: 

54

The parameter is either 0 or 1. If is 0, then detector 

responsivity data is used to calculate readings. If is 1, then the detector 

+ attenuator responsivity data is used to calculate readings. 

Function: 

This command enables or disables the use of attenuator responsivity data. If 

enabled, responsivity data collected with the attenuator attached to the 

detector is used in data calculations. If disabled, responsivity data collected 

with the detector alone is used in data calculations. 

This command will generate an error if the attached detector does not support 

an attenuator. 

Related Commands: ATTN?, ATTNSN?, LAMBDA, LAMBDA?, RESP?, USRCAL, 

USRCAL?, USRRESP, USRRESP? 

ATTN? 

Attenuator Calibration Data Enable Query 

Syntax: ATTN? 


Function: 

This query returns a value showing whether or not attenuator responsivity 

data is currently being used. 

Returns: 

is of type which represents the integer 0 if detector 

responsivity data is being used or 1 if detector + attenuator responsivity data 

is being used. 

Related Commands: ATTN?, ATTNSN?, LAMBDA, LAMBDA?, RESP?, USRCAL, 

USRCAL?, USRRESP, USRRESP? 

ATTNSN? 

Attenuator Serial Number Query 

Syntax: ATTNSN? 


Function: 

This query returns the serial number of the attenuator that was calibrated 

with the attached detector. 

When using an attenuator this serial number must match the serial number of 

the attenuator being used or data calculations will be inaccurate. 

Returns: 

is of type in the double quote format. If no attenuator serial 

number is available, the query returns an empty double quoted string, “”. 

Related Commands: CALDATE?, DETMODEL?, DETSN? 

55

AUTO 

Auto Ranging Enable 

Syntax: AUTO 

Parameters: 

The parameter is either 0 or 1. If is 0 then manual ranging is 

enabled. If is 1 then auto ranging is enabled. 

Function: 

This command enables or disables auto ranging. If enabled and in a continuous 

acquisition mode, a signal range is automatically selected to suit the input 

signal. If disabled, the meter needs to be manually ranged. 

Related Commands: AUTO?, RANGE, RANGE? 

AUTO? 

Auto Ranging Enable Query 

Syntax: AUTO? 


Function: 

This query returns a value showing whether the meter is in auto ranging 

feature is enabled or disabled. 

Returns: 

is of type which represents the integer 0 if auto ranging is 

disabled or 1 if auto ranging is enabled. If enabled, the meter will auto range 

when in continuous acquisition modes. 

Related Commands: AUTO, RANGE, RANGE? 

BARGRAPH 

Bar Graph Enable 

Syntax: BARGRAPH 

Parameters: 

The parameter is either 0 or 1. If is 0 then the bargraph is 

disabled. If is 1 then the bargraph is enabled. 

Function: 

This command enables or disables the bargraph feature. If enabled, the 

bargraph will be displayed when the units of measurement are not ratio type 

of units and the meter is not in INTG mode. 

Related Commands: BARGRAPH?, TONE, TONE? 

BARGRAPH? 

Bar Graph Enable Query 

Syntax: BARGRAPH? 


56

Function: 

This query returns a value showing whether the bargraph is enabled or 

disabled. Note: The bargraph is not displayed while in either GPIB or RS-232 

mode regardless of enabled status. 

Returns: 

is of type which represents the integer 0 if the bar graph is 

disabled and 1 if the bar graph is enabled. 

Related Commands: BARGRAPH, TONE, TONE? 

CALDATE? 

Calibration Date Query 

Syntax: CALDATE? 


Function: 

This query returns the calibration date of the detector as read from the 

memory module attached to the 1835-C. 

Returns: 

is of type in the double quote format. 

Related Commands: ATTNSN?, DETMODEL?, DETSN? 

DETMODEL? 

Detector Model Query 

Syntax: DETMODEL? 


Function: 

This query returns the model number of the detector that belongs to the 

memory module attached to the 1835-C. 

Returns: 


Related Commands: ATTNSN?, CALDATE?, DETSN? 

DETSN? 

Detector Serial Number Query 

Syntax: DETSN? 

Parameter: None 

Function: 

This query returns the serial number of the detector that the memory module 

belongs to. This serial number must match the serial number of the detector 

attached to the 1835-C. 

Returns: 


Related Commands: ATTNSN?, CALDATE?, DETMODEL? 

57

DETSW 

Detector Switch Setting 

Syntax: DETSW 

Parameter: 

is of type in a double quoted format. The possible values of 

are “S” for short, “I” for intermediate, and “L” for long. 

Function: 

The 818J-S10 and the 818J-09 have a switch setting for short, intermediate and 

long energy pulse measurement. This command must be used to inform the 

1835-C what the switch is set to when using these detectors. 

If the attached detector doesn’t support a switch then this command will 

cause an execution error. 

Related Commands: DETSW? 

DETSW? 

Detector Switch Setting Query 

Syntax: DETSW? 

Parameter: None 

Function: 

This query returns the switch setting assumed by the 1835-C. This setting 

must match the actual switch setting on the detector or readings will be 

inaccurate. 

Returns: 

is of type in the double quote format. The possible values 

of are “S” for short, “I” for intermediate, and “L” for long. If the 

attached detector doesn’t support a switch the return value will be “N/A”. 

Related Commands: DETSW 

DISP 

Display Brightness 

Syntax: DISP 

Parameters: 

The parameter is of type which rounds to an integer in the 

range 0 to 2. 0 corresponds to off, 1 to dim, 2 to normal, and 3 to bright. 

Function: 

This command sets the brightness of the display to a desired level. The valid 

levels are off, dim, normal, and bright. 

Returns: None 

Related Commands: DISP? 

58

DISP? 

Display Brightness Query 

Syntax: DISP? 


Function: 

This query returns the brightness level of the display. 

Returns: 

is of type where 0 corresponds to off, 1 to dim, 2 to normal, 

and 3 to bright. 

Related Commands: DISP 

DS? 

Data Store Value Query 

Syntax: DS? 

Parameters: 

The parameter rounds to an integer and represents the data store 

value that is being queried. The range of is 1 to n; where n is the 

number of values stored in the data store buffer (see DSCNT?). A parameter 

of 1 represents the oldest data value in the data store, 2 the second oldest and 

so on. 

Function: 

This query is used to query an individual data value from the data store 

buffer. If the parameter is out of range then an execution error message will 

be generated and nothing will be returned. It is recommend to use the 

DSCNT? query to determine how many values have been stored in the data 

buffer. 

Returns: , 

is an integer that represents the status of the returned value. 

will be 0 for ok, 1 for over range, 2 for detector saturated, 3 for data error 

and 4 for ranging. 

is a floating point number in the exponential format. 

Related Commands: DSCLR, DSCNT?, DSE, DSE?, DSSIZE, DSSIZE?, DSUNITS?, 

DSBUF, DSBUF? 

DSBUF 

Data Store Buffer Behavior Select 

Syntax: DSBUF 

Parameters: 


range -32768 to 32767. If the number rounds to 0 then data store FIXED 

BUFFER behavior is enabled. Otherwise, data store SLIDE BUFFER behavior is 

enabled. 

59

Function: 

This command selects data store FIXED BUFFER or SLIDE BUFFER behavior. 

Related Commands: DS?, DSCLR, DSCNT?, DSE, DSE?, DSSIZE, DSSIZE?, 

DSUNITS?, DSBUF? 

DSBUF? 

Data Store Buffer Behavior Query 

Syntax: DSBUF? 


Function: 

This query returns a value showing whether data store FIXED BUFFER or 

SLIDE BUFFER behavior is enabled. 

Returns: 

is of type and represents an integer 0, if FIXED BUFFER 

behavior is enabled, or 1, if data store SLIDE BUFFER behavior is enabled. 


DSUNITS?, DSBUF 

DSCLR 

Data Store Clear 

Syntax: DSCLR 


Function: 

This command is used to clear the data store buffer. 

Related Commands: DS?, DSCNT?, DSE, DSE?, DSSIZE, DSSIZE?, DSUNITS?, 

DSBUF, DSBUF? 

DSCNT? 

Data Store Value Count Query 

Syntax: DSCNT? 


Function: 

This query returns the number of data values stored in the data store buffer. 

Returns: 

is of type and represents an integer in the range of 1 to the 

size of the data store buffer. 

Related Commands: DS?, DSCLR, DSE, DSE?, DSSIZE, DSSIZE?, DSUNITS?, 

DSBUF, DSBUF? 

60

DSE 

Data Store Enable 

Syntax: DSE 

Parameters: 

The parameter is a which is either 0 or 1. If the number is 0, 

data storing is disabled. If the number is 1, data storing is enabled. 

Function: 

This command enables or disables data storing. 

Note that data storing can not be enabled when the data store buffer is full 

and FIXED BUFFER behavior is enabled. The user must first either clear the 

data store buffer or enable SLIDE BUFFER behavior and then enable data 

storing. 

Related Commands: DS?, DSCLR, DSCNT?, DSE?, DSSIZE, DSSIZE?, DSUNITS?, 

DSBUF, DSBUF? 

DSE? 

Data Store Enable Query 

Syntax: DSE? 


Function: 

This query returns a value showing whether or not data storing is enabled or 

disabled. 

Returns: 

is of type and represents an integer 0, if data storing is 

disabled, or 1, if data storing is enabled. 

Related Commands: DS?, DSCLR, DSCNT?, DSE, DSSIZE, DSSIZE?, DSUNITS?, 

DSBUF, DSBUF? 

DSSIZE 

Data Store Buffer Size Select 

Syntax: DSSIZE 

Parameters: 


range 1 to 2500. The parameter represents the size of the data buffer to be 

used for data storing. 

Function: 

This command sets the size of the buffer used for data storing. Note that the 

data buffer is cleared automatically when this command is used and all 

previously stored data will be gone. 

Related Commands: DS?, DSCLR, DSCNT?, DSE, DSE?, DSSIZE?, DSUNITS?, 

DSBUF, DSBUF? 

61

DSSIZE? 

Data Store Buffer Size Query 

Syntax: DSSIZE? 


Function: 

This query returns the data store buffer size. 

Returns: 

is of type and represents an integer of the range 1 to 2500. 

Related Commands: DS?, DSCLR, DSCNT?, DSE, DSE?, DSSIZE, DSUNITS?, 

DSBUF, DSBUF? 

DSUNITS? 

Data Store Buffer Units Query 

Syntax: DSUNITS? 


Function: 

This query returns the units of the data stored in the data store buffer. 

Returns: 


The possible values of units are: “A”, “V”, “W”, “W/CM”, “dBm”, “dB”, “REL”, 

“J”, “J/CM”, “Erg”, or “E/CM” depending on the detector and acquisition mode. 


DSBUF, DSBUF? 

ECHO 

RS-232 Echo Mode Enable 

Syntax: ECHO 

Parameters: 

The parameter is either 0 or 1. If is 0 then RS-232 echo mode is 

disabled. If is 1 then RS-232 echo mode is enabled. 

Function: 

This command enables or disables the echo mode for RS-232 communication. 

Related Commands: ECHO? 

ECHO? 

RS-232 Echo Mode Enable Query 

Syntax: ECHO? 


Function: 

This query returns a value showing whether the RS-232 echo mode is enabled 

or disabled. 

62

Returns: 

is of type that represents the integer 0, if the echo mode is 

disabled, or 1, if the echo mode is enabled. 

Related Commands: ECHO 

EVENT? 

Device Event Register Query 

Syntax: EVENT? 


Function: 

This query returns the contents of the Device Event register and sets the 

Device Event register to 0. The *CLS command will also set this register to 0. 

The Device Event register is AND’ed with the Device Event Enable register. If 

any bit is set in the result of this AND’ing operation then Device Error bit (bit 

3) in the Standard Event Status register will be set. 

The Device Event register is an 8 bit, bit mapped register, with each bit 

signifying a different condition. The bits are listed below, most significant bit 

first: 

7 

6 

5 

4 

3 

2 

1 

0 

Over Range 

Saturated 

Data Error 

(Not Used) 

(Not Used) 

(Not Used) 

(Not Used) 

(Not Used) 

Device Event Register 

Returns: 

is an integer in the range from 0 to 255 inclusive. 

Related Commands: *ESE, *ESE?, *ESR?, EVENTEN, EVENTEN?, 

EVENTEN 

Device Event Enable Register 

Syntax: EVENTEN 

Parameters: 


is written into the Device Event Enable register. 

Function: 

The Device Event Enable register is AND’ed with the Device Event register. If 

any bit is set in the result of this AND’ing operation then Device Error bit (bit 

3) in the Standard Event Status register will be set. 

63

The Device Event Enable register is an 8 bit, bit mapped register. Any bit set 

to 1 in the Device Event Enable register allows the corresponding bit in the 

Device Event register to set the Device Error bit (bit 3) in the Standard Event 

Status register. Any bit set to 0 disables the corresponding bit in the Device 

Event register from setting the Device Error it. 

7 

6 

5 

4 

3 

2 

1 

0 

Over Range 

Saturated 

Data Error 

(Not Used) 

(Not Used) 

(Not Used) 

(Not Used) 

(Not Used) 


Related Commands: EVENT?, EVENTEN?, *ESE, *ESE?, *ESR? 

EVENTEN? 

Device Event Enable Register Query 

Syntax: EVENTEN? 


Function: 

This query returns the contents of the Device Event Enable register. See the 

EVENTEN command for a description of the Device Event Enable register. 

Returns: 

is of type and represents an unsigned decimal integer in the 

range from 0 to 255. 

Related Commands: EVENT?, EVENTEN, *ESE, *ESE?, *ESR? 

EXT 

External Trigger Enable 

Syntax: EXT 

Parameters: 

The parameter is either 0 or 1. If is 0 then the external trigger 

is disabled. If is 1 then the external trigger is enabled. 

Function: 

This command enables or disables the external trigger input on the back 

panel. 

Related Commands: EXT?, EXTEDGE, EXTEDGE? 

EXT? 

External Trigger Enable Query 

Syntax: EXT? 


64

Function: 

This query returns a value showing whether the external trigger input enabled 

or disabled. 

Returns: 

is of type that represents the integer 0, if the external 

trigger input is disabled, or 1, if the external trigger is enabled. 

Related Commands: EXT, EXTEDGE, EXTEDGE? 

EXTEDGE 

External Trigger Edge Select 

Syntax: EXTEDGE 

Parameters: 

The parameter is either 0 or 1. If is 0 then the external trigger 

is defined as a falling edge. If is 1 then the external trigger is defined as 

a rising edge. 

Function: 

This command defines whether the external trigger input on the back panel is 

falling edge or rising edge active. 

Related Commands: EXT, EXT?, EXTEDGE 

EXTEDGE? 

External Trigger Edge Query 

Syntax: EXTEDGE? 


Function: 

This query returns a value showing which external trigger edge is the active 

edge. 

Returns: 

is of type and represents the 0, if the external trigger is 

defined as a falling edge, or 1, if the external trigger is defined as a rising edge. 

Related Commands: EXT, EXT?, EXTEDGE 

FILTER 

Filter Select 

Syntax: FILTER 

Parameters: 

The parameter is an integer in the range 0 to 3 inclusive. 0 corresponds 

to no filtering, 1 to analog filter only, 2 to digital averaging filter only, 

and 3 to analog and digital filters combined. 

Function: 

This command selects a filter combination to be used to condition readings 

taken from the detector. The choices are to have no filter at all, an analog 

filter, digital averaging filter, and both the analog and digital filters. The digital 

filter processes every signal reading by averaging it with the last 9 readings 

taken. 

65

All detectors signals are filtered to some extent even without the analog filter 

feature. By enabling the analog filter the signal is filtered by a 5 Hz low pass 

instead of the standard filter. The analog filter feature only applies to Low 

Power detectors when not in P-P mode. For High Power and Energy detectors, 

the analog filter feature is not available. 

If an attempt is made to enable the analog filter for a detector that does not 

support it, an execution error will occur. 

Related Commands: FILTER? 

FILTER? 

Filter Query 

Syntax: FILTER? 


Function: 

This query returns a value that represents the filter combination currently 

being used to condition readings. 

Returns: 

is of type in a range of 0 to 3 with 0 corresponding to no 

filter, 1 to analog filter only, 2 to digital averaging filter only, and 3 to analog 

and digital filters combined. 

This query will always return a 0 or 2 for High Power and Energy detectors 

because the use of the analog filter is not allowed with these types of detectors. 

Related Commands: FILTER 

LAMBDA 

Lambda Select 

Syntax: LAMBDA 

Parameters: 

The parameter is of type which rounds to an integer 

with a range that depends on the detector being used. The units of 

is nanometers and should correspond to the wavelength of the light 

source being measured. 

Function: 

This command is used to specify the wavelength of light being measured. 

This will insure that the proper responsivity calibration point will be used 

when the 1835-C calculates measurement values. 

Related Commands: ATTN, ATTN?, LAMBDA?, RESP?, USRCAL, USRCAL?, 

USRRESP, USRRESP? 

LAMBDA? 

Lambda Query 

Syntax: LAMBDA? 


66

Function: 

This query returns the wavelength that corresponds to the responsivity 

calibration point currently being used by the 1835-C in measurement 

calculation. 

Returns: 

is of type and represents an integer. The units of 

is nanometers. 

Related Commands: ATTN, ATTN?, LAMBDA, RESP?, USRCAL, USRCAL?, 


LLO 

Local Lockout Enable 

Syntax: LLO 

Parameters: 

The parameter is either 0 or 1. If is 0 then local lock-out is 

disabled. If is 1 then local lock-out is enabled. 

Function: 

This command enables or disables the local lockout. 

Returns: None 

Related Commands: LLO? 

LLO? 

Local Lockout Enable Query 

Syntax: LLO? 


Function: 

The query returns the state of the local lockout. 

Returns: 

is of type and represents the integer 0, if local lockout is 

disabled, or 1, if local lockout is enabled. 

Related Commands: LLO 

MODE 

Acquisition Mode Select 

Syntax: MODE 

Parameters: 

The parameter is of type . Its range depends on the detector 

attached to the meter. The valid values for this parameter are listed below. 

67

“DCSNGL” specifies DC single mode 

“DCCONT” specifies DC continuous mode 

“INTG” 

specifies integration mode 

“PPSNGL” specifies P-P single mode 

“PPCONT” specifies P-P continuous mode 

“SNGLPULSE” specifies single pulse mode 

“CONTPULSE” specifies continuous pulse mode 

Function: 

This command sets the mode to be used to acquiring subsequent readings. 

Note that the current units may be changed if they are not compatible with 

the new mode. 

Related Commands: MODE?, UNITS, UNITS? 

MODE? 

Acquisition Mode Query 

Syntax: MODE? 


Function: 

This query returns the acquisition mode currently being used by the meter. 

Returns: 


Related Commands: MODE, UNITS, UNITS? 

R? 

Read Query 

Syntax: R? 


Function: 

This query returns the last valid measurement taken. The units of this 

measurement are the units defined at the time the reading was made. Because 

it is possible to make this query faster than measurements are actually 

being taken, the values returned by successive queries may be multiple 

reports of a single measurements. 

To ensure that fresh data is being read the NVDA(new valid data available) bit 

in the Status Byte can be checked either by issuing a serial poll or by using the 

*STB? command. A serial poll is recommended if the GPIB interface is being 

used. The NVDA bit will be 1 if the last valid measurement has not been read. 

The bit is set to 0 immediately after this query, or the RWS? query, is executed 

and will stay 0 until a new valid reading is taken by the meter. A valid reading 

is a reading that would return a status of 0 using the RWS? query. 

Returns: 


Related Commands: *STB?, MODE, MODE?, RWS?, UNITS, UNITS? 

68

RANGE 

Signal Range Select 

Syntax: RANGE 

Parameters: 

The parameter is of type . A value of 0 represents the 

smallest signal range available for the current configuration of the meter. 

Function: 

This command is used to select a new manual signal range. This command 

will disable the auto ranging feature. 

Related Commands: AUTO, AUTO?, RANGE? 

RANGE? 

Signal Range Query 

Syntax: RANGE? 


Function: 

This query returns a value that represents the current signal range setting 

being used whether the meter is auto ranging or in manual ranging mode. 

Returns: 

is of type and represents the gain level currently being 

used for either auto or manual ranging. A value of 0 represents the smallest 

signal range. 

Related Commands: AUTO, AUTO?, RANGE 

REFVAL 

Reference Value Select 

Syntax: REFVAL 

Parameters: 

The parameter is of type . 

Function: 

This command provides a means of directly storing a reference value to be 

used in linear and logarithmic (dB) relative measurements. The units of this 

value are watts for Low Power and High Power detectors and joules for Energy 

detectors. 

Related Commands: REFVAL?, STOREF 

REFVAL? 

Reference Value Query 

Syntax: REFVAL? 


Function: 

This query returns the last stored reference value. This value will be in watts 

for Low-Power and High-Power detectors and joules for Energy detectors. 

69

Returns: 

is of type in exponential notation. 

Related Commands: REFVAL, STOREF 

RESP? 

Responsivity Query 

Syntax: RESP? 


Function: 

This query returns the responsivity value currently being used by the 1835-C 

in measurement calculation. 

Returns: 

is of type and represents a floating point number. The units 

of the responsivity depends upon the type of detector family of the 

detector in use. See Table 22 for a listing of responsivity units by detector 

family. 

Related Commands: ATTN, ATTN?, LAMBDA, LAMBDA?, USRCAL, USRCAL?, 


RUN 

Start Acquisition 

Syntax: RUN 


Function: 

This command initiates the acquisition of data in the currently defined 

acquisition mode. In single type acquisition modes the RUN command will 

cause one reading to be acquired. In continuous type acquisition modes the 

RUN command will initiate the continuous acquisition of readings. The STOP 

command will terminate acquisition. 

Related Commands: STOP 

RWS? 

Read With Status Query 

Syntax: RWS? 


Function: 

This query returns the last measurement taken. The units of this measurement 

are the units defined at the time the reading was made. Because it is 

possible to make this query faster than measurements are actually being 

taken, the values returned by successive queries may be multiple reports of 

the same measurement. 

To ensure that fresh data is being read the NDA(new data available) bit in the 

Status Byte can be checked either by issuing a serial poll or by using the 

*STB? command. A serial poll is recommended if the GPIB interface is being 

used. The NDA bit will be 1 if the last measurement data has not been read. 

70

The bit is set to 0 immediately after this query, or the R? query, is executed 

and will stay 0 until a new reading is taken by the meter. This query will also 

set the NVDA bit to 0. 

Returns:, 

is an integer that represents the status of the returned value. 

will be 0 for ok, 1 for over range, 2 for saturated and 3 for data error, and 

4 for ranging. 


Related Commands: *STB?, MODE, MODE?, R?, UNITS, UNITS? 

SFREQ 

DC Sample Frequency Select 

Syntax: SFREQ 

Parameters: 

The parameter is of type . The range of this number depends 

on the current DC sample precision (see SPREC). If the precision is 20000 then 

the range is 0.001 to 25Hz. If the precision is 4096 then the range is 0.001 to 

1000Hz. 

Function: 

This command determines how often a signal is sampled when in DC continuous 

mode. 

Related Commands: SFREQ?, SPREC, SPREC? 

SFREQ? 

DC Sample Frequency Query 

Syntax: SFREQ? 


Function: 

This query returns the sample rate used for continuous DC acquisition. 

Returns: 

is of type in exponent notation with units of hertz or samples 

per second. 

Related Commands: SFREQ, SPREC, SPREC? 

SPREC 

DC Sample Precision Select 

Syntax: SPREC 

Parameters: 

The parameter is of type and with acceptable values of 

20000 or 4096. 

Function: 

The 1835-C has a 20,000 count high precision A/D and a 4,096 count A/D. This 

command determines which of these A/Ds will be used to acquire samples 

during DC single and DC continuous acquisition modes. This command 

affects the available range of DC sample frequencies. 

71

Note that the 4,096 count A/D is used during all other acquisition modes. 

Related Commands: SFREQ, SFREQ?, SPREC? 

SPREC? 

DC Sample Precision Query 

Syntax: SPREC? 


Function: 

This query returns a string that indicates whether the 20,000 count A/D or the 

4,096 count A/D will be used during DC CONT or DC SNGL acquisition modes. 

Returns: 

is of type . It will be 20000 if the 20,000 count A/D is select 

and 4096 if the 4,096 count A/D is selected. 

Related Commands: SFREQ, SFREQ?, SPREC? 

STMAX? 

Statistics Buffer Maximum Value Query 

Syntax: STMAX? 


Function: 

This query returns the maximum value in the statistics buffer. 

Returns: 

is of type in exponent notation. 

Related Commands: STMEAN?, STMIN?, STMXMN?, STSDEV?, STSIZE, 

STSIZE?, 

STMEAN? 

Statistics Buffer Mean Value Query 

Syntax: STMEAN? 


Function: 

This query returns the mean or average of all the values in the statistics 

buffer. 

Returns: 


Related Commands: STMAX?, STMIN?, STSDEV?, STMXMN?, STSIZE, STSIZE? 

STMIN? 

Statistics Buffer Minimum Value Query 

Syntax: STMIN? 


72

Function: 

This query returns the minimum value in the statistics buffer. 

Returns: 


Related Commands: STMAX?, STMEAN?, STSDEV?, STMXMN?, STSIZE, 

STSIZE? 

STMXMN? 

Statistics Buffer Max-Min Query 

Syntax: STMXMN? 


Function: 

This query returns the difference between the maximum and minimum 

readings in the statistics buffer. 

Returns: 


Related Commands: STMAX?, STMEAN?, STMIN?, STMXMN, STSIZE, STSIZE? 

STSDEV? 

Statistics Buffer Standard Deviation Query 

Syntax: STSDEV? 


Function: 

This query returns the standard deviation of the readings in the statistics 

buffer. 

Returns: 


Related Commands: STMAX?, STMEAN?, STMIN?, STMXMN, STSIZE, STSIZE? 

STSIZE 

Statistics Buffer Size Select 

Syntax: STSIZE 

Parameters: 


range of 0 to 100. The parameter represents the size of the statistics buffer. 

Function: 

This command sets the size of the buffer used for calculating real-time statistics. 

The contents of this buffer are updated every time a reading is taken. 

The statistics buffer is cleared automatically when this command is issued or 

when the acquisition mode or units are changed. 

If the buffer size is set to 0 then the statistics are disabled and no statistical 

information will be maintained. 

Related Commands: STMAX?, STMEAN?, STMIN, STSIZE?, STSDEV? 

73

STSIZE? 

Statistics Buffer Size Query 

Syntax: STSIZE? 


Function: 

This query returns the statistics buffer size. 

Returns: 

is of type and represents an integer in the range 0 to 100. 

Related Commands: STMAX?, STMEAN?, STMIN, STMSMN?, STSDEV?, STSIZE 

STOP 

Stop Acquisition 

Syntax: STOP 


Function: 

This command terminates any acquisition of data currently in progress. If the 

meter is not acquiring data then this command has no effect. 

Related Commands: RUN 

STOREF 

Store Reference Reading 

Syntax: STOREF 


Function: 

This command takes the latest reading and stores it as a reference reading to 

be used when making relative linear and dB measurements. The units of the 

reference reading defaults to Watts for Low-Power and High-Power detectors 

and Joules for Energy detectors. 

Related Commands: REFVAL, REFVAL? 

STOZERO 

Store Zero Signal 

Syntax: STOZERO 


Function: 

This command takes the latest reading and stores it as a zero signal reference 

value to be used when zeroing is enabled. The units of the zero reference 

defaults to Amperes for Low-Power detectors and Volts for High-Power and 

Energy detectors. 

Related Commands: ZERO, ZERO?, ZEROVAL? 

74

TONE 

Tone Enable 

Syntax: TONE 

Parameters: 

The parameter is which can be 0 or 1. If the number is 0 

then the tone is disabled. If the number is 1, then tone is enabled. 

Function: 

This command enables or disables a tone feature that emits a short audible 

“tick” when a peak or pulse is detected in peak-to-peak or pulse acquisition 

modes. 

This command will cause an error if the detector does not support peak-topeak 

or pulse acquisition modes. 

Related Commands: TONE? 

TONE? 

Tone Enable Query 

Syntax: TONE? 


Function: 

This query returns a value indicating whether the tone feature is not available, 

enabled or disabled. 

Returns: 

is a which can be -1, 0 or 1. If -1 then the tone feature is not 

available for the detector in use. If 0 then the tone feature is disabled. If 1 

then the tone feature is enabled. 

Related Commands: TONE 

TRIGOUT 

Trigger Out Mode Select 

Syntax: TRIGOUT 

Parameters: 

The parameter is of type . The valid values for this parameter 

are listed below. 

“CMPLT” specifies conversion complete mode 

“FREQ” 

specifies frequency mode 

“LVL” 

specifies level comparator mode 

“INTG” 

specifies integration level mode 

“OFF” 

specifies off mode 

Function: 

This command determines in which mode the trigger out output on the 

backpanel will operate. 

Certain modes require additional parameters to be set. 

Related Commands: TRIGOUT, TRIGOUT?, TRIGOUTFREQ, TRIGOUTFREQ?, 

TRIGOUTINTG, TRIGOUTINTG?, TRIGOUTLVL, TRIGOUTLVL?, TRIGOUTPOL, 

TRIGOUTPOL? 

75

TRIGOUT? 

Trigger Out Mode Query 

Syntax: TRIGOUT? 


Function: 

This query returns the current mode of the trigger out output. 

Returns: 


Related Commands: TRIGOUT, TRIGOUTFREQ, TRIGOUTFREQ?, 

TRIGOUTINTG, TRIGOUTINTG?, TRIGOUTLVL, TRIGOUTLVL?, TRIGOUTPOL, 

TRIGOUTPOL? 

TRIGOUTFREQ 

Trigger Out Frequency Select 

Syntax: TRIGOUTFREQ 

Parameters: 

The parameter is of type . The range of this number is 0.001 

to 1000Hz. 

Function: 

This command is used to set the frequency at which a pulse is output, on the 

trigger out, in trigger out frequency mode. 

Related Commands: TRIGOUT, TRIGOUT?, TRIGOUTFREQ?, TRIGOUTINTG, 

TRIGOUTINTG?, TRIGOUTLVL, TRIGOUTLVL?, TRIGOUTPOL, TRIGOUTPOL? 

TRIGOUTFREQ? 

Trigger Out Frequency Query 

Syntax: TRIGOUTFREQ? 


Function: 

This query returns the trigger out pulse frequency used during trigger out 

frequency mode. 

Returns: 

is of type in exponent notation with units of hertz. 

Related Commands: TRIGOUT, TRIGOUT?, TRIGOUTFREQ, TRIGOUTINTG, 

TRIGOUTINTG?, TRIGOUTLVL, TRIGOUTLVL?, TRIGOUTPOL, TRIGOUTPOL? 

TRIGOUTINTG 

Trigger Out Integration Level Select 

Syntax: TRIGOUTINTG 

Parameters: 

The parameter is of type which specifies an integration 

energy level in joules. 

76

Function: 

This command is used to set the integration energy level at which the trigger 

out will become inactive if using the trigger out in integration mode. 


TRIGOUTINTG, TRIGOUTLVL, TRIGOUTLVL?, TRIGOUTPOL, TRIGOUTPOL? 

TRIGOUTINTG? 

Trigger Out Integration Level Query 

Syntax: TRIGOUTINTG? 


Function: 

This query returns the trigger out integration energy level at which the trigger 

out will become inactive if using the trigger out in integration acquisition 

mode. 

Returns: 

is of type in exponent notation with units of joules. 


TRIGOUTINTG, TRIGOUTLVL, TRIGOUTLVL?, TRIGOUTPOL, TRIGOUTPOL? 

TRIGOUTLVL 

Trigger Out Level Select 

Syntax: TRIGOUTLVL 

Parameters: 

The parameter is of type . The units of this parameter are 

Watts for Low-Power and High-Power detectors and Joules for Energy detectors. 

Function: 

This command is used to set the level used by the trigger out level comparator 

mode. When the power, or energy level is at or above this level the trigger 

out will go to its active state. 


TRIGOUTINTG, TRIGOUTINTG?, TRIGOUTLVL?, TRIGOUTPOL, TRIGOUTPOL? 

TRIGOUTLVL? 

Trigger Out Level Query 

Syntax: TRIGOUTLVL? 


Function: 

This query returns the trigger out level used by the trigger out level comparator 

mode. 

77

Returns: 

is of type in exponent notation with units of Watts for Low- 

Power and High-Power detectors and Joules for Energy detectors. 


TRIGOUTINTG, TRIGOUTINTG?, TRIGOUTLVL, TRIGOUTPOL, TRIGOUTPOL? 

TRIGOUTPOL 

Trigger Out Polarity Select 

Syntax: TRIGOUTPOL 

Parameters: 

The parameter is a which can be 0 or 1. If the number 

rounds to 0, then the polarity will be active low. If the number is 1, then the 

polarity will be active high. 

Function: 

This command is used to set the polarity of the trigger out output to either 

active low or active high. 


TRIGOUTINTG, TRIGOUTINTG?, TRIGOUTLVL, TRIGOUTLVL?, TRIGOUTPOL? 

TRIGOUTPOL? 

Trigger Out Polarity Query 

Syntax: TRIGOUTPOL? 


Function: 

This query returns a value that indicates whether the trigger out polarity is 

active high or active low. 

Returns: 

is of type and represents the integer 0, if the polarity is 

active low, or 1, if the polarity is active high. 


TRIGOUTINTG, TRIGOUTINTG?, TRIGOUTLVL, TRIGOUTLVL?, TRIGOUTPOL 

UNITS 

Units Select 

Syntax: UNITS 

Parameters: 

is of type . All possible values of units are listed below: 

“V” 

specifies volts 

“A” 

specifies amps 

“W” 

specifies watts 

“W/cm” specifies watts/cm 2 

“dBm” 

specifies dBm 

“dB” 

specifies dB 

“REL” 

specifies linear ratio 

78

“J” 

specifies joules 

“J/cm” specifies joules/cm 2 

“ERG” 

specifies ergs 

“E/cm” specifies ergs/cm 2 

A subset of these units will be valid for particular detector and acquisition 

mode. 

Function: 

Sets the units to be used for subsequent measurements. Once the units have 

been set, all new readings are given in the new units. 

Related Commands: MODE, MODE?, UNITS? 

UNITS? 

Units Query 

Syntax: UNITS? 


Function: 

This query returns the units of readings currently being taken. 

Returns: 


The possible values of units are: “A”, “V”, “W”, “W/cm”, “dBm”, “dB”, “REL”, 

“J”, “J/cm”, “ERG”, or “E/CM” depending on the detector and acquisition 

mode. 

Related Commands: MODE, MODE?, UNITS 

USRCAL 

User Calibration Enable 

Syntax: USRCAL 

Parameters: 

The parameter is a which can be 0 or 1. If the number is 0, 

then user calibration is disabled. If the number is 1, then user calibration is 

enabled. 

Function: 

This command enables or disables the use of a user defined calibration point. 

Related Commands: ATTN, ATTN?, LAMBDA, LAMBDA?, RESP?, USRCAL?, 


USRCAL? 

User Calibration Enable Query 

Syntax: USRCAL? 


79

Function: 

This query returns a value showing whether or not user calibration is enabled 

or disabled. 

Returns: 

is of type and represents an integer 0, if user calibration is 

disabled, or 1, if user calibration is enabled. 

Related Commands: ATTN, ATTN?, LAMBDA, LAMBDA?, RESP?, USRCAL, 


USRRESP 

User Responsivity Factor Select 

Syntax: USRRESP 

Parameters: 

The parameter is of type . The units of this parameter match 

the responsivity units of the detector in use. 

Function: 

This command is used to define a responsivity factor that will be used by the 

1835-C in measurement calculation when user calibration is enabled. 


USRCAL?, USRRESP? 

USRRESP? 

User Responsivity Factor Query 

Syntax: USRRESP? 


Function: 

This query returns the user defined responsivity factor that will be used by 

the 1835-C in measurement calculation when user calibration is enabled. 

Returns: 

is of type and represents a floating point number. The units 

of match the responsivity units of detector in use. 


USRCAL?, USRRESP 

ZERO 


Syntax: ZERO 

Parameters: 

The parameter is a which can be 0 or 1. If the number is 0, 

then readings are not adjusted by the stored zero reference. If the number is 

1, then readings are adjusted by the stored zero reference. 

80

Function: 

This command enables or disables the zeroing feature. Zeroing causes the 

stored zero reference (see STOZERO command) to be subtracted from 

incoming signal readings before the incoming signal is used in measurement 

calculations. 

Related Commands: STOZERO, ZERO?, ZEROVAL 

ZERO? 


Syntax: ZERO? 


Function: 

This query returns a value showing whether or not zeroing is enabled or 

disabled. 

Returns: 

is of type and represents the integer 0, if zeroing is enabled, 

or 1, if zeroing is disabled. 

Related Commands: STOZERO, ZERO, ZEROVAL 

ZEROVAL? 

Zero Signal Query 

Syntax: ZEROVAL? 


Function: 

This query returns the current value being used for zeroing. 

Returns: 

is of type in exponential notation. The units of this value 

are the numerator of the detector’s responsivity, i.e. amps for Low Power 

detectors and volts for High Power and Energy detectors. 

Related Commands: STOZERO, ZERO, ZERO? 

81

Section 6 

Maintenance, Test 

and Troubleshooting 

6.1 Maintenance Procedures 

In cleaning the body of this instrument, use only a mild soap and water 

solution on a damp cloth. 

CAUTION 

Do not use acetone or other organic solvents (other than alcohol) on the 

Model 1835-C Multi-Function Optical Meter. Organic solvents attack the 

paint. 

6.2 Power Up Self Test 

The Model 1835-C executes a system self test after every power up or reset 

and indicates on the display whether the self test has been passed. If the self 

test is not passed the display will indicate one of the following error messages: 

“CAL MODULE ERROR” 

“REGISTER ERROR” 

“INTG A/D ERROR” 

“SA A/D/ ERROR” 

“KEYPAD ERROR” 

If “CAL MODULE ERROR” appears, check to see that the module is properly 

inserted. 

Should any other message appear, call Newport Corporation’s Customer 

Service Department. 

6.3 Troubleshooting Guide 

The following troubleshooting guide is intended to isolate and solve problems 

with the power meter so that, to the greatest extent possible, the return of the 

power meter/detector system to Newport will be unnecessary. For the 

82

problems that cannot be resolved with information in this manual, or for other 

situations that are not covered in this section, please see Section 7 for details 

on returning your entire system to Newport for service. 

Symptom 

Blank display. 

Display shows “OL” 

Display shows “SA” 

Display shows “- - - - -” 

Any of the following messages: 

“REGISTER ERROR” 

“INTG A/D ERROR” 

“SA A/D ERROR” 

“KEYPAD ERROR” 

The display shows: 

“CAL MODULE ERROR” 

and “MISSING OR BAD” 


“CAL MODULE ERROR” and 

“CHECKSUM ERROR” 

Table 27. Symptom/Fault Troubleshooting Guide 

Possible Fault/Correction 

Power switch OFF. Turn switch ON. 

Power cord connection is absent. Check 

power cord connection. 

Indicates that the signal is too large for the 

selected signal range. Select a higher 

RANGE or use an attenuator if one is 

available. 

Indicates that the signal exceeds the 

detector saturation or damage threshold. 

Select a detector with higher power or 

energy handling capability or use an 

attenuator if one is available. 

Indicates that the meter is in the middle of 

a range change or that the current units 

don’t match the units of the last reading. 

Call Newport Corporation’s Customer 

Service Department and arrange to return 

the unit for repair. 

Make sure the CAL MODULE is seated 

correctly and reset the meter. Try a 

second CAL MODULE, if one is available, to 

localize the problem to the first CAL 

MODULE. 

If the first CAL MODULE does not work 

after proper seating and reset, but the 

second CAL MODULE works, call Newport 

Customer Service and arrange for a repair 

of the first CAL MODULE. 

If neither the first or second CAL MODULE 

works, call Newport Customer Service and 

arrange for a meter repair. Be sure to also 

return the first CAL MODULE if you cannot 

otherwise determine that it is working. 

Call Newport Customer Service and 

arrange to return the meter for repair. 

83


“BATTERY FAILURE” 

Call Newport Customer Service and 

arrange to return the meter for battery 

replacement. 

RS-232 communication does Check the RS-232 cable connection and 

not seem to work 

cable pinouts, Figure 17. Make sure that 

the device talking to the meter is setup for 

8 data bits, no parity, and 1 stop bit. Also 

check the echo mode state. 

No listener error when 

Check the GPIB cable connections and 

attempting GPIB 

the GPIB address. 

communications 

Display value does not change. Press the R/S key. 

Reading is different than 

See Table 23 Common Measurement 

expected. Errors. Section 3.10.6. 

84

Section 7 

Factory Service 


This section contains information regarding obtaining factory service for the 

Model 1835-C Multi-Function Optical Meter. The user should not attempt any 

maintenance or service of this instrument and/or accessories beyond the 

procedures given in Section 6: Maintenance, Test and Troubleshooting. Any 

problems which cannot be resolved using the guidelines listed in Section 6 

should be referred to Newport Corporation factory service personnel. Contact 

Newport Corporation or your Newport representative for assistance. 

The Model 1835-C contains no user serviceable parts. Its calibration accuracy 

is warranted for a period of 1 year. After 1 year, the unit should be returned to 

Newport Corporation for recalibration and NIST traceability recertification. 

7.2 Obtaining Service 

To obtain information concerning factory service, contact Newport Corporation 

or your Newport representative. Please have the following information 

available: 

1. Instrument model number (On front panel) 

2. Instrument serial number (On rear panel) 

3. Description of the problem. 

If the instrument is to be returned to Newport Corporation, you will be given a 

Return Number, which you should reference in your shipping documents. 

Please fill out the service form, located on page 87, and have the information 

ready when contacting Newport Corporation. Return the completed service 

form with the instrument. 

85

Service Form 

Newport Corporation 

U.S.A. Office: 949/863-3144 

FAX: 949/253-1800 

Name _____________________________________________________________________________________ 

Company _______________________________________________________________________________ 

RETURN AUTHORIZATION # _____________________________ 

(Please obtain prior to return of item) 

Address _________________________________________________________________________________ 

Country _________________________________________________________________________________ 

P.O. Number ___________________________________________________________________________ 

Date _________________________________________________________________ 

Phone Number _________________________________________________ 

Item(s) Being Returned: 

Model # ___________________________________________________________________ 

Serial # ______________________________________________________________________________ 

Description __________________________________________________________________________________________________________________________________________________________ 

Reason for return of goods (please list any specific problems) ______________________________________________________________________________ 

____________________________________________________________________________________________________________________________________________________________________________ 

List all control settings and describe problem _______________________________________________________________________________________________________ 

____________________________________________________________________________________________________________________________________________________________________________ 

____________________________________________________________________________________________________________________________________________________________________________ 

_______________________________________________________________________________________________________________(Attach additional sheets as necessary). 

Show a block diagram of your measurement system including all instruments connected (whether power is turned 

on or not). Describe signal source. If source is a laser, describe output mode, peak power, pulse width, repetition 

rate and energy density. 

Where is the Measurement Being Performed? 

(factory, controlled laboratory, out-of-doors, etc.) _________________________________________________________________________________________________ 

What power line voltage is used? ________________________________________________ 

Variation? ________________________________________________________ 

Frequency? ___________________________________________________ 

Ambient Temperature? ________________________________________________________________ 

Variation? ________________________________________ °F. Rel. Humidity? ___________________________________ 

Other? ________________________________________ 

Any additional information. (If special modifications have been made by the user, please describe below). 

____________________________________________________________________________________________________________________________________________________________________________ 

____________________________________________________________________________________________________________________________________________________________________________ 

____________________________________________________________________________________________________________________________________________________________________________ 

____________________________________________________________________________________________________________________________________________________________________________ 

87

Appendix A 

Syntax and Definitions 

A.1 Definition of 

The IEEE 488.2 standard defines two type of string data. These strings are 

either single or double quoted. For convenience, the 1835-C also recognizes 

an unquoted string with certain restrictions as detailed below. Any of these 

forms may be used where a parameter is required. 

1. , using double quotes. “this is a string” 

2. , using single quotes. ‘this is a string’ 

3. , using no quotes. thisisastring 

A description of each type of follows: 

1. defined using double quotes. 

A double quote indicates that a string follows, and the string is terminated 

by another double quote. A double quote may be embedded 

within the string by using two double quotes together: 

Example: “this string contains a “” double quote” 

All characters within the two outer double quotes are considered part 

of the string. It is an error if the string does not terminate with a double 

quote. The string cannot contain the (ascii decimal 13), (ascii 

decimal 10), or End Of Identify characters. 

2. string> defined using single quotes. 

This form is similar to double quoted string. A single quote indicates 

that a string follows, and the string is terminated by another single 

quote. A single quote may be embedded within the string by using two 

single quotes together: 

Example: ‘this string contains a ‘’ single quote’ 

All characters within the two outer single quotes are considered part of 

the string. It is an error if the string does not terminate with a single 

quote. The string cannot contain the (ascii decimal 13), (ascii 

decimal 10), or End Of Identify characters. 

3. defined using no quotes. 

All strings using this format must start with an alphabetic character (A 

through Z, a through z). All other characters must be either alphabetic, 

digit (0 through 9) or the ‘_’ character. Any other character will 

deliminate the string. 

89

Some examples are shown below: 

Sent: this is a string 

Interpreted: this (1st string) 

is 

(2nd string) 

a 

(3rd string) 

string 

(4th string) 

Sent: this,isastring 

Interpreted: this (1st string) 

, (separator character) 

isastring 

(2nd string) 

Sent: w/cm 

Interpreted: w (1st string) 

ERROR 

(unrecognized character) 

cm 

(2nd string) 

A.2 Definition of 

The IEEE 488.2 standard defines four different types of numeric data. The 

1835-C recognizes all four types as number>, thus any format may be used. 

1. defined as floating point. 

2. defined as binary. 

3. defined as octal. 

4. defined as hexadecimal. 

Where necessary, integers are converted to floating point numbers. In all 

cases, a number is terminated by any of the below characters: 

, ; 

Any non-valid characters detected in any number received are considered an 

error in format, and an error condition will be generated in the system. There 

are no differences between the 1835-C and IEEE-488.2 standard for number 

definition. 

A description of each type of follows: 

1. defined as floating point. 

Any of the following characters, as the first character of an ASCII sequence, 

indicates that a number is being defined: 

+ − . 0 1 2 3 4 5 6 7 8 9 

A floating point number is defined as follows: 

1. Optional + − sign. This defines the sign of the number. If missing, 

positive is assumed. 

2. Optional 0 - 9 digits. These digits define the integer portion of the 

mantissa. 

3. Optional . decimal point. This defines the end of the integer portion 

of the mantissa, and indicates that the fractional portion of the 

mantissa follows. 

90

4. Optional 0 - 9 digits. These digits define the fractional portion of the 

mantissa. 

5. Optional exponent indicator, an ASCII ‘E’ or ‘e’, followed by a ‘+’ or ‘−’ 

(optional), followed by decimal digits. 

Examples: 

the numbers below all represent the value “1.2” 

1.2 

1.2e0 

+01.2E+00000 

120E-2 

.12e1 

the numbers below all represent the value “−1.2” 

−1.2 

−1.2e+00 

−0001.2e+0 

−120e-2 

.12E1 

2. defined as binary. 

The 1835-C recognizes unsigned binary numbers in the range of 0 to 

65535, decimal, or 0 to 1111111111111111 binary. Binary numbers are 

represented using only the digits 0 and 1. A binary number has the 

following format: 

#B 

Where 

#B = mandatory binary number header 

= binary digits (0’s or 1’s) 

Example: 

All numbers below represent the decimal value 129. 

#B10000001 

#b010000001 

#b10000001 

91

3. defined as octal. 

The 1835-C recognizes unsigned octal numbers in the range 0 to 65535 

decimal, or 0 to 177777 octal. Octal numbers are represented using 

digits from 0 to 7. An octal number has the following format: 

#Q 

Where 

#Q = mandatory octal number header 

= octal digits (0 to 7) 

Example: 


#Q201 

#q0201 

#q201 

4. defined as hexadecimal. 

The 1835-C recognizes unsigned hexadecimal numbers in the range 0 to 

65535 decimal, or 0 to FFFF hexadecimal). Hexadecimal numbers are 

represented using the digits 0 - 9 and the characters A - F. A hexadecimal 

number has the following format: 

#H 

Where 

#H = mandatory octal number header 

= hexadecimal digits (0 - 9 and A - F) 

Example: 


#H7f 

#H007F 

#h7f 

92

Appendix B 

Error Messages 

The IEEE 488.2 standard defines certain bits in the status registers as error 

condition flags. When an error occurs, one of the error bits is set in the status 

registers. The bit enable masks and the service request enable allow the 1835- 

C to alert the remote controller that an error has occurred. The standard 

allows error numbers that range from -100 to -499. 

When using the RS-232C port the RS-232 Echo Mode controls when errors are 

returned. When the Echo Mode is enabled the errors are returned immediately. 

When the Echo Mode is disabled the errors are not returned immediately 

and the *ERR? command must be used to retrieve the errors. 

B.1 Command Errors 

Command Errors are associated with the conversion of the data received into 

the commands and their parameters (parsing). Incorrect syntax, incorrect 

parameters, and improper command format will generate these errors. Any 

command error will cause the Command Error bit (bit 5) in the Standard 

Event Status Byte to be set. 

-102,“Syntax error” 

Occurs when an error in command structure or parameter type is detected. 

Some typical causes are: 

Using a number as a command mnemonic. 

Using the wrong parameter type. 

Using ASCII characters outside of a string constant that are not defined by 

the command language syntax. 

Missing or too many parameters. 

The above list in not exhaustive but does give the basic idea of what to look 

for. 

-110,“Command header error” 

This error is generated when the system parser detects an invalid character in 

a command header. 

-113, “Undefined Header” 

This error is generated when the 1835-C does not recognize a command 

header. 

93

-121,“Invalid character in number” 

This error indicates that a numeric parameter contains an invalid character or 

a character in the wrong place. The only characters allowed in a number are: 

0-9 e E . + − 

When using the binary number format, the only characters allowed are: 

0 1 

When using the octal number format, the only characters allowed are: 

0 1 2 3 4 5 6 7 

When using the hexadecimal number format, the only characters allowed are: 

0-9 A-F a-f 

-150,“String data error” 

This error is generated when the system parser detects an error in string type 

data. 

-151,“Invalid string data” 

Usually caused by an error in string termination. The IEEE 488.2 standard 

defines all quoted strings as having a closing quote. If the closing quote is 

missing, usually due to a character being embedded in the string, this 

error will be generated. 

-191,“Out of string space” 

Generated when the system parser runs out of space for commands and 

parameters. It may occur if commands are not terminated correctly. 

-192,“Out of token space” 

Occurs when the system parser detects more command elements (headers 

and parameters) than it can handle. It may also occur if commands are not 

terminated correctly. 

B.2 Execution Errors 

Execution Errors are associated with the interpretation of the converted 

commands and parameters received. Incorrect parameter values and numerical 

range errors are types of execution errors. Any execution error will cause 

the Execution Error bit (bit 4) in the Standard Event Status Byte to be set. 

-220,“Parameter error” 

This is a general parameter error. If this error occurs the parameter may be 

invalid or inappropriate. 

-222,“Data out of range” 

This error will occur if a parameter is out of a valid range or not in the set of 

valid parameters for a given command. 

94

-286,“Configuration not compatible” 

This error will occur if an attempt is made to recall a system configuration 

that is not compatible with the detector currently attached to the meter. 

-287,“Configuration not available” 

This error will occur if an attempt is made to recall a system configuration 

that has not been saved to and is therefore not available. 

-288,“Command not available” 

This error will occur if an attempt is made to use a command that is not 

available for the detector in use. 

B.3 Device Errors 

Device Errors are associated with some system condition that affects the 

operation of the meter. Errors associate with data reading will set the appropriate 

bit but will not generate an error message to avoid jamming the error 

queue or the interface 

95

Appendix C 

Status Reporting System 

On this page is a graphical representation of the status reporting system for 

the GPIB and RS-232 port communications. Following, is a detailed description 

of each register and how the bits are set and reset. The interactions 

between registers is discussed as well as the generation of a GPIB Service 

Requests. 

C.1 Status Reporting System Flowchart 

Not Used 

Not Used 

Not Used 

Not Used 

AND 

Not Used 

Data Error 

Saturated 

Overrange 

Device Event Register 7 6 5 4 3 2 1 0 EVENT? 

Device Event Enable Register 

7 6 5 4 3 2 1 0 

EVENTEN 

EVENTEN? 

OR 

Execution Error Bit 

Command Error Bit 

(Not Used) User Request Bit 

(Not Used) Power On Bit 

Standard Event Status Register 7 6 5 4 3 2 1 0 *ESR? 

AND 

Device Error Bit 

Query Error Bit 

Register Control Bit (Not Used) 

Operation Complete Bit 

Standard Event Enable Register 

7 6 5 4 3 2 1 0 

*ESE 

*ESE? 

Request for Service 

OR 

IEEE 488.1 

Serial Poll Response 

Message Available Bit 

Event Status Byte Bit 

Service Request Bit 

Error Queue Bit 

Status Byte Register 7 6 5 4 3 2 1 0 *STB? 

Not Defined by IEEE 488.2 

Not Defined by IEEE 488.2 



Service Request 

Enable Register 

AND 

7 6 5 4 3 2 1 0 

OR 

*SRE 

*SRE? 

Parallel Poll 

Enable Register 

AND 

7 6 5 4 3 2 1 0 

OR 

*PRE 

*PRE? 

*IST? 

IEEE 488.1 

Service Request 

 

 

96

C.2 Device Event Register 

The Device Event Register is used to record device errors associated with 

some system condition that affects the operation of the meter. When a bit is 

set (has a value of one) then the condition is true. The bit remains set until 

cleared by the EVENT? query or *CLS command. 

The Device Event Enable Register is used to define the conditions that will set 

the Device Error bit in the Standard Event Status register. If a bit is set in the 

Device Event Register and its corresponding bit is set in the Device Event 

Enable Register, then the Device Error bit in the Standard Event register will 

be set. 

The Device Event Enable Register is configured by using the EVENTEN command. 

The Device Event Register is described below. The register is bit mapped, 

with each bit representing the described condition. The bits are listed most 

significant bit first. 


bit 7-bit 3: Not Currently Used. 

bit 2: Data Error 

A one in this bit indicates that a data error occurred during reading 

calculations. These errors will include such conditions as divide by 

zero or taking the log of a negative number. 

bit 1: Saturated 

Many detectors contain information in their CAL MODULE that indicates 

when the detector saturates or is otherwise over driven. A one in this 

bit indicates that a reading was taken at or above this saturation level. 

bit 0: Overrange Error 

A one in this bit indicates that an overrange condition occurs when 

taking a reading. 

C.3 Standard Event Status Register 

The Standard Event Status Register is used to record general system event 

conditions for the status reporting system. The register is bit mapped, 

meaning that each condition is represented by a bit. When a bit is set (has a 

value of 1), then the condition is true. The bit remains set until cleared by the 

*ESR? query or the *CLS command. 

The Standard Event Enable Register is used to define the conditions that will 

set the Event Status Byte bit (bit 5) in the Status Byte. If a bit is set in the 

Standard Event Status register and its corresponding bit is set in the Standard 

Event Enable Register, then the Event Status Byte bit (bit 5) in the Standard 

Event Register will be set. 

The Standard Event Enable Register is configured by using the *ESE common 

command. 

97

Each of the bits in the Standard Event Status Register is described below. 

Standard Event Status Register 

bit 7: Power On Not used by the 1835-C. 

bit 6: User Request Not used by the 1835-C. 

bit 5: Command Error 

A 1 in this bit indicates that the 1835-C has received a remote command 

that generated a command error. 

bit 4: Execution Error 

A 1 in this bit indicates that the 1835-C has received a remote command 

that generated an execution error. 

bit 3: Device Error 

A 1 in this bit indicates that an unmasked device error has occurred. 

bit 2: Query Error 

A 1 in this bit indicates that a query error has occurred. 

bit 1: Request Control This bit is always 0. 

bit 0: Operation Complete 

This bit is controlled by the *OPC command. If the *OPC command is in 

effect, then this bit will be set to 1 when all pending operations have 

completed. To operate correctly, this bit should be cleared by the *CLS 

command or *ESR? query before the *OPC command is issued again. 

C.4 Status Byte 

The Status Byte register is used to record a summary of current system 

conditions for the status reporting system. It is returned to the controller 

when a serial poll of the 1835-C is conducted or when the *STB? query is 

issued. The register is bit mapped, meaning that each condition is represented 

by a bit. When a bit is set, or has a value of 1, then the condition is 

true. The bits are cleared based on the conditions described for each bit. 

The Service Request Enable register is used to define the conditions that will 

generate a IEEE 488.1 . When an event occurs that causes a bit to be set 

in the Status Byte register and its’ corresponding bit is set in the Service 

Request Enable register, then a will be generated when that bit is set. 

The Service Request Enable Register is configured by using the *SRE common 

command. 

The Parallel Poll Enable Register is used with the Status Byte to generate the 

message. If any bit is set in the Status Byte and it’s corresponding bit is 

set in the Parallel Poll Enable Register, then the message is set true (a 

value of one). Otherwise the message is set false (a value of zero). 

When a parallel poll is conducted with the 1835-C configured to respond to it, 

the message is compared to the (sense bit). If they are the same 

then the configured data line will be driven true in response to the parallel poll. 

98

Both the and the data line driven during a parallel poll can be selected 

by the IEEE 488.1 parallel poll remote configuration command. 

The Parallel Poll Enable Register is configured by using the *PRE command. 

The Status Byte Register is described below. 

Status Byte 

bit 7: Error Queue 

A one in this bit indicates that the error queue is not empty (see the 

*ERR? query). The *CLS command will empty the error queue and, as a 

result, this bit. 

bit 6: Service Request/Master Summary Status 

When the status byte is read by means of a serial poll, this bit is set 

when the 1835-C is requesting service. 

When the status byte is read by means of the *STB? query, this bit will 

be set if any bit in the status byte is set and its corresponding bit is set 

in Service Request Enable Register. 

bit 5: Event Status Byte 

The Event Status Byte bit is set when a bit in the Standard Event Status 

register is set and its corresponding bit in the Standard Event Enable 

register is set. The *CLS command or *ESR? query will clear the Standard 

Event Status register and, as a result, this bit. 

bit 4: Message Available 

The Message Available MAV bit becomes set when any message is 

ready to be transmitted over the GPIB interface (not the RS-232 interface). 

Once the message is sent, the MAV bit is cleared. A GPIB device 

clear command will clear the output queue and, as a result, this bit. 

NOTE: After a query is issued over the GPIB interface this bit should be 

checked by means of a serial poll before attempting to read the query 

response. 

bit 3: Not used 

bit 2: Not used 

bit 1: New Valid Data Available 

The New Valid Data Available NVDA bit becomes set when a new 

reading has been taken by the 1835-C that is not overrange, did not 

saturate the detector, did not cause a data error and was not taken 

while ranging. It is cleared by the R? or RWS? queries. 

bit 0: New Data Available 

The New Data Available NDA bit becomes set when a new reading has 

been taken by the 1835-C. It is cleared by the R? or RWS? queries. 

99

Appendix D 

Sample Programs 

D.1 Example Program: RS-232C Communication 

10 ‘********************* Program Header *************************** 

20 ‘NEWPORT CORPORATION 

30 ‘1835-C to RS232 Communication Program - an example program 

40 ‘ 

50 ‘This program is designed to show you how to write a simple 

60 ‘program that will write commands and read query responses to and 

70 ‘from the 1835-C Multi-Function Optical Meter via the RS-232 port on the 

80 ‘Rear Panel and the RS-232 port on an IBM PC/AT or compatible. The 

90 ‘Program was written in MICROSOFT GWBASIC on an IBM AT compatible. 

100 ‘ 

110 ‘Written By: Darwin D. Smith 

120 ‘ Date: April 28, 1993 

130 ‘************************* End of Header ************************* 

1000 ‘Beginning of program 

1010 ‘Open COM port with the following specifications: 

1020 ‘COM port 1, 9600 baudrate, no parity, 8 data bits & 1 stop bit 

1030 OPEN “COM2:9600,N,8,1” FOR RANDOM AS #1 

1040 GOSUB 2000 ‘Draw header on the screen 

1050 GOSUB 3000 ‘Process user input 

1060 CLOSE #1 ‘Close the COM file 

1070 END ‘End of program 

1080 ‘ 

2000 ‘Main.Screen: Draw the main screen. 

2010 CLS 

2020 LOCATE 1, 20: PRINT “N E W P O R T C O R P O R A T I O N” 

2030 LOCATE 2, 20: PRINT “1835-C to RS-232 Communication Program” 

2040 LOCATE 3, 20: PRINT “ q or Q to Quit” 

2050 RETURN 

2060 ‘ 

3000 ‘Enter.User.Commands: Get and interpret the user’s commands. 

3010 WHILE (1) ‘Get and process user input until Q or q is input. 

3020 RS232OUT$ = “” ‘Clear RS232out$ string 

3030 LINE INPUT RS232OUT$ ‘Get the user input 

3040 IF RS232OUT$ = “Q” OR RS232OUT$ = “q” THEN RETURN ELSE GOSUB 4000 

3050 ‘Assume strings ending with “?” are queries 

3060 IF INSTR(RS232OUT$, “?”) = 0 THEN GOTO 3090 

3070 GOSUB 5000 

3080 ‘END IF 

3090 WEND 

3100 RETURN 

3110 ‘ 

4000 ‘Write.RS232.String: Write the string RS232OUT$ to the RS232 port 

4010 PRINT #1, RS232OUT$ ‘PRINT # appends to the string 

4020 RETURN 

4030 ‘ 

5000 ‘Read.RS232.String: Read a string from the 1835-C RS232 port. 

5010 ‘Characters are read one at a time until a character is 

5020 ‘read or 8 seconds elapse between consecutive character reads. 

5030 ‘At the end of the routine the string read is in RS232IN$. 

5040 BUFFER$ = CHR$(0) ‘Initialize buffer$ to NULL character 

5050 RS232IN$ = “” 

5060 TIMEOUT.ERROR% = 0 ‘Initiate to no timeout error 

5070 ON TIMER(8) GOSUB 6000 ‘Set timer for a 1 second time out 

5080 TIMER ON ‘Turn on timer 

5090 ‘While port doesn’t timeout and string deliminator not 

100

5100 ‘read, continue trying to read input on COM port. 

5110 WHILE TIMEOUT.ERROR% = 0 AND BUFFER$ CHR$(10) 

5120 IF LOC(1) = 0 THEN GOTO 5170 

5130 TIMER OFF 

5140 BUFFER$ = INPUT$(1, #1) 

5150 RS232IN$ = RS232IN$ + BUFFER$ 

5160 TIMER ON 

5170 ‘END IF 

5180 WEND 

5190 TIMER OFF 

5200 IF TIMEOUT.ERROR% = 0 THEN GOTO 5230 

5210 PRINT “Timed out when reading RS-232 port.” 

5220 TIMEOUT.ERROR% = 0 

5230 ‘ELSE 

5240 PRINT RS232IN$; 

5250 ‘END IF 

5260 RETURN 

5270 ‘ 

6000 ‘timeout: Set TIMEOUT.ERROR% flag. Called if t seconds, as 

6010 ‘defined by ON TIMER(t), in the Read.RS232.String, has elapsed 

6020 ‘between TIMER ON AND TIMER OFF. 

6030 TIMEOUT.ERROR% = 1 

6040 RETURN 

10000 END ‘End of Program Listing 

101

D.2 Example Program: IEEE-488 Communication 

‘*********************** Program Header ******************************* 

‘NEWPORT CORPORATION 

‘1835-C to IEEE-488 Communication Program - an example program 

‘ 

‘The following program is designed to be an example of how to write a simple 

‘program that will write commands and read query responses to and from 

‘the 1835-C Multi-Function Optical Meter via the IEEE-488 port. 

‘ 

‘This program was written on an IBM AT compatible using QuickBASIC 4.5 

‘ and software routines included with the GPIB board. 

‘The GPIB board used was: National Instruments GPIB-PC2A board 

‘ Newport Corporation pn LA-PC-488-2A-5 

‘The interface cable was: Newport Corporation pn LA-CABLE-2M488 

‘ 

‘NOTE: Before running this program follow National Instrument’s instructions 

‘ for hardware and software installation. This program uses the GPIB 

‘ configuration device named DEV5 which uses GPIB address 5 by default. 

‘ All routines that begin with the letters “IB” are defined in the 

‘ National Instruments library. 

‘ 

‘Written By: Darwin D. Smith 

‘ Date: April 28, 1993 

‘************************* End of Header ************************************ 

‘Beginning of program 

‘$INCLUDE: ‘E:\b45\QBDECL4.BAS’ 

‘Use your own path here. 

‘Beginning of program 

IEEEout$ = “DEV5” 

‘Use this name or assign a new one 

CALL IBFIND(IEEEout$, device.number%) ‘Setup the device.number% variable 

‘used in GPIB-PC routine calls. 

IF device.number% < 0 THEN 

PRINT “Unable to find “; IEEEout$; “ device.” 

STOP 

END IF 

GOSUB Main.Screen 

‘Draw header on the screen 

GOSUB Enter.User.Commands 

‘Process user input 

END ‘End of program 

‘Main.Screen: Draw the main screen. 

Main.Screen: 

CLS 

LOCATE 1, 22: PRINT “N E W P O R T C O R P O R A T I O N” 

LOCATE 2, 19: PRINT “1835-C to IEEE-488 Communication Program” 

LOCATE 3, 19: PRINT “ 

Q or q to Quit” 

RETURN 

‘Enter.User.Commands: Get and interpret the user’s commands. 

Enter.User.Commands: 

DO ‘Get and process user input until Q, or QUIT input. 

IEEEout$ = “” 

‘Clear IEEEout$ string 

LINE INPUT IEEEout$ 

‘Get the user input 

IEEEout$ = UCASE$(IEEEout$) 

‘Convert input to upper case 

SELECT CASE IEEEout$ 

CASE “Q”, “QUIT” 

‘Exit on Q 

RETURN 

CASE “IBCLR” 

‘Allow a device clear 

CALL IBCLR(device.number%) 

CASE “IBRSP” 

‘Allow a serial poll 

CALL IBRSP(device.number%, poll%) 

PRINT poll% 

CASE ELSE 

GOSUB Write.IEEE.String 

‘Write user input to IEEE port 

IF INSTR(IEEEout$, “?”) 0 THEN ‘If command was a query 

GOSUB Read.IEEE.String 

‘ Read input data on IEEE port 

END IF 

END SELECT 

LOOP WHILE 1 = 1 

RETURN 

102

‘Write.IEEE.String: Write the string IEEEout$ out to the IEEE port. 

Write.IEEE.String: 

IEEEout$ = IEEEout$ + CHR$(10) 

‘Append a to IEEEout$ 

CALL IBWRT(device.number%, IEEEout$) ‘Write IEEEout$ to IEEE-488 port 

RETURN 

‘Read.IEEE.String: Read a string from the PMC200P IEEE port. The string 

‘ read from the IEEE-488 port is printed on the screen. If the MAV bit 

‘ in the status byte doesn’t go high after 8 seconds then this routine 

‘ will timeout. Otherwise the query response is in IEEEin$ 

Read.IEEE.String: 

timeout.error% = 0 

‘Initiate to no timeout error 

poll% = 0 

IEEEin$ = SPACE$(255) 

‘Initiate IEEEin$ to 255 spaces 

ON TIMER(8) GOSUB timeout 

‘wait for MAV bit in the status byte to be set or a timeout to occur 

TIMER ON 

WHILE ((poll% AND &H10) = 0) AND (timeout.error% = 0) 

CALL IBRSP(device.number%, poll%) 

WEND 

TIMER OFF 

IF (timeout.error% = 1) THEN 

PRINT “IEEE-488 port timed out when trying to read input.” 

ELSE 

CALL IBRD(device.number%, IEEEin$) ‘Read IEEE-488 port 

IEEEin$ = RTRIM$(IEEEin$) 

‘Trim trailing spaces 

END IF 

RETURN 

PRINT IEEEin$; 

‘Print the query response 

‘timeout: Set timeout.error% flag. This routine is called if t seconds, 

‘as defined by the ON TIMER(t) function call, has elapsed between TIMER ON 

‘and TIMER OFF. 

timeout: 

timeout.error% = 1 

RETURN 

END ‘End of Program Listing 

103

Newport Corporation 

Worldwide Headquarters 

1791 Deere Avenue 

Irvine, CA 92606 

(In U.S.): 800-222-6440 

Tel: 949-863-3144 

Fax: 949-253-1680 

Internet: sales@newport.com 

Visit Newport Online at: www.newport.com 

Newport Corporation, Irvine, California, has 

been certified compliant with ISO 9001 by 

the British Standards Institution. 

104 

P/N 20061-01, Rev. D 

IN-05931 (02-00) 

Printed in the USA

Model 1835-C - Newport Corporation

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