Siemeca AMR â¢ Network Node WTT16/WTX16 M-Bus ... - Armatec AB

Siemeca AMR ® 

Network Node WTT16/WTX16 

M-Bus Specification 

31.08.2006 For intra-company use only 

Återförsäljare: 

ARMATEC AB 

Box 9047 

SE_400 91 Göteborg, SWEDEN

Abstract: 

This document describes how to communicate on the M-bus with a network node (up to 

V2.1) made by Siemens Building Technologies electronic. The document has been created 

to support customer-specific applications. 

This document must not be copied and/or shared with or distributed to third parties without 

approval from Siemens Building Technologies electronic GmbH. 

Siemens 

Building Technologies electronic GmbH 

HVP-IP 

Sondershäuser Landstr. 27 

99974 Mühlhausen/Thüringen 

Tel: +49 (3601) 46 83-0 

Fax: +49 (3601) 46 83-34 

www.siemens.com/siemeca 

©2006 Siemens Building Technologies AG 

Subject to change 

2/56 For intra-company use only 

Siemens 

Netzwerkknoten WTT16/WTX16 

Building Technologies Contents 09.03.2007

Contents 

1 General Remarks about the M-Bus ........................... 5 

2 References................................................................. 10 

3 The Network Node..................................................... 11 

3.1 Physical Layer............................................................. 12 

3.2 Data Link Layer ........................................................... 14 

3.3 Application Layer......................................................... 21 

3.4 Special Network Node Commands ............................. 34 

4 Meters......................................................................... 41 

4.1 Current Data (Memory Block #0) ................................ 42 

4.2 Cutoff Date Data (Memory Block #1) .......................... 44 

4.3 Statistical Data (Memory Block ≥ #8) ......................... 45 

4.4 Overview of Data Points for Siemeca Meter Statistics 46 

5 Annex ......................................................................... 47 

5.1 M-Bus Ranges............................................................. 47 

5.2 Types of M-Bus Telegrams ......................................... 48 

5.3 Meter Readout from Network Node ............................ 50 

For intra-company use only 3/56 

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1 General Remarks about 

the M-Bus 

M-Bus 

Architecture 

Feeding of M-Bus 

The M-bus is a pure master / slave bus, i.e., the master determines 

when communication takes place and which data are transmitted. An 

M-bus slave is not capable, for example, of transmitting a message 

on its own to the master in the event of an error. The M-bus design 

allows the production of low-cost and, most of all, energy-saving 

slaves, i.e., meters. This is of crucial importance for ensuring that 

meters will be operational for a period of many years. 

The M-bus – slave interface is fed by the bus and has a defined 

current consumption of 1.5 mA. This current consumption is called 

one M-bus load. In order to feed the actual meter, more power can 

be drawn from the M-bus, so that current consumption may exceed 

1.5 mA. Consequently, the meter will operate with more than one M- 

bus load. This fact is important for dimensioning the M-bus system. 

A repeater or an M-bus master is able to drive a certain number of 

M-bus devices (with one M-bus load). Whenever a meter draws 

several M-bus loads, the number of devices to be connected must 

be reduced accordingly or a repeater must be employed. The M-bus 

standard allows a device to draw up to four M-bus loads. The 

number of M-bus loads should be looked up in the operating 

instructions for the devices concerned. 

The bus is protected against polarity reversal for easy installation. In 

other words, thanks to the voltage-modulated signal that the master 

uses to the slaves, the polarity of the two leads does not matter 

when the device is connected. The slaves, for their part, respond 

with a current-modulated signal. There is a significant disadvantage 

to it, too. Communication is possible only between the master and 

the slave. A slave can never receive the current-modulated signals 

of another slave. 


Siemens 


Building Technologies General Remarks about the M-Bus 09.03.2007

M-Bus Topology 

The topology of an M-bus connection can be flexibly adjusted to the 

conditions in the field. For this reason, both pure lines or bus 

structures and a star topology can be used. No form of ring topology 

is permitted, however. 

M-Bus Range 

The M-bus is a long-range bus capable of linking meters to the M- 

bus master via a two-wire connection that extends over several 

kilometers. The range of the M-bus line is mainly determined by the 

capacity of the cable and the diameter. The greater the cable 

capacity per 100 meters of cable and the smaller the cross-section 

of the line used, the shorter the range will be. Accordingly, a parallel 

connection of several M-bus lines (star topology) will equally reduce 

the maximum range. If the range within an existing cable network 

needs to be increased, it helps to operate the meters at a 

transmission rate of 300 bauds instead of the preset 2,400 bauds. 

(See also Annex.) Another way to extend the range is to use an M- 

bus repeater. Such a device receives the signals from the M-Bus 

master in the first M-bus segment and transmits them in the second 

M-bus segment to the slaves in an amplified manner (and vice 

versa). Additionally, it assures the feeding of the second M-bus 

segment, with the number of loads that can be connected depending 

both on that segment and on transmission loss. Maximum M-bus 

ranges are listed in the Annex. If the loads available are not 

sufficient, additional repeaters may be connected in series or in 

parallel. 


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M-Bus Spezifikation 


M-Bus Data 

Transmission 

Format 

Example: 

M-Bus Addressing 

Primary Address 

Under the Intel format (little endian), data points greater than one 

byte are transmitted with the least significant byte first. Within a byte, 

however, bits are transmitted with the most significant bit first (bit 7). 

A consumption value 123456 (BCD-coded) would be transmitted on 

the M-bus in the following sequence: 56 34 12. Therefore, binary 

transmission would be “01010110 00110100 00010010” (without 

showing any start, stop and parity bits). 

An M-bus device (slave) may have two addresses: 

• Primary address 

• Secondary address 

The primary address is determined with the aid of the service tool 

when the devices are installed. Numbers from 0 to 250 may be 

assigned to a primary address. Thus, a maximum of 251 devices 

can be addressed on a primary address M-bus. Primary address "0“ 

is preset by the manufacturer. It should always be changed during 

installations, so that a device you may have forgotten will still be 

found in a search run. 

Primary address "253" indicates that the secondary address is used 

for identifying the M-bus device. The secondary address is 

transmitted in the application layer. 

Address "254" is used as a test address. This means that every M- 

bus device will always respond to this address, irrespective of its 

own primary address. For this reason, the test address may only be 

used when exactly one M-bus slave is connected to the bus. 

Otherwise, collisions will occur when device responses are sent 

back. 

Address "255" is used as broadcast address. This means that all the 

M-bus devices connected to the bus receive and process the 

command from the master. However, no receipt confirmation will be 

sent back to the master in that case. For this reason, the broadcast 

address should not be employed to parameterize important settings. 

There are devices where the primary address cannot be changed. 

Such devices can only be addressed through an M-bus master 

which supports secondary addresses. 


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Secondary Address 

The secondary address is a globally unambiguous number assigned 

by the manufacturer. 

The secondary address in the M-bus consists of four parts: 

• Device identification (device ID = consecutive number, e.g., 

12345678) 

• Manufacturer's ID (unambiguous code identifying the 

manufacturer, e.g., 12901 = "LSE") 

• Version (software version of the device) 

• Medium (physical measurand of the device, e.g., 6 = "hot water") 

In the secondary address, the maximum number of devices is limited 

only by the characteristics of the cable and the storage capacity of 

the M-bus master. M-bus systems administered through the 

secondary address may comprise several thousand devices. A 

detailed description of the secondary address is provided on 

Page 18. 


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M-Bus Standard 

The OSI 

Reference Model 

The M-bus was first standardized with the heat meter in EN1434-3 

[5]. Since 2005, the M-bus has been standardized in EN13757, 

together with the COSEM Protocol, as a standard in its own right. 

The M-bus itself is governed by EN13757-2 [2] and EN13757-3 [3]. 

In the last few years, a specific model has gained general 

acceptance for the description of communication between two 

machines. 

Its underlying idea is to 

separate the various functions 

or layers of communication 

and to assign them to 

different functional blocks. 

However, not all of those 

seven layers are really 

needed or implemented in 

every communication link. 

The M-bus standard only 

provides for the following 

layers: 

• Application layer [3] 

• Data link layer [2], [4] 

• Physical layer [2], [4] 

The description of the data link layer relates almost entirely to [1] in 

this context. 

This document is structured according to the three OSI layers 

supported. For an understanding of the M-bus protocol, knowledge 

of the application layer of the M-bus is indispensable. If the creation 

of a separate M-bus master is intended, purchase of the European 

standard EN13757 listed in the next section is recommended. (The 

requirements to be met by the hardware are described in [2], while 

the protocol is set out in [3]. 


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2 References 

[1] EN60870-5-2 Telecontrol equipment and systems – Part 5: 

Transmission protocols, Main Section 2: Link 

transmission procedures 

[2] EN13757 – 2 Communication systems for remote reading 

of meters – Part 2: Physical and link layers 


of meters – Part 3: Dedicated application 

layer 


of meters – Part 4: Wireless meter readout 

(radio meter reading for operation in the 

868 MHz to 870 MHz SDR band) 

[5] EN1434 – 3 Heat meters – Part 3: Data exchange and 

interfaces 

[6] Data Sheet „Siemeca AMR Remote Meter Readout 

System – Data Points of Meters“ 

Internet download: 

An older version of [2] is available at: 

http://www.m-bus.com/files/W4A21021.pdf, 

while an older version of [3] can be downloaded from: 

http://www.m-bus.com/files/W4B21021.pdf. 


Siemens 


Building Technologies References 09.03.2007

3 The Network Node 

Radio and M-Bus 

Devices 

The network node (without 

gateway) is a system device 

whose job it is to receive and 

store the data from radioing 

meters and to make them 

available for the readout 

process. 

M-Bus 

virtual M-BUS 

Since the M-bus is a pure 

master-slave bus, which does 

not allow messages from the 

slave to the master to be sent 

spontaneously, the data 

received via radio are stored. 

The M-bus master is in a 

position at any time to call up 

a copy of the data. 

As a general principle, an M- 

bus master cannot access the 

radio channel directly. In 

order to make the stored radio 

device accessible to the M-bus master, the network node simulates 

the existence on the bus of each radioing meter received as a "real" 

M-bus device. Consequently, the M-bus master addresses the meter 

directly and also gives the appearance of receiving a response 

directly from the meter. In other words, the master is not "aware" 

that, in reality, it is communicating with an entirely different device. 

As a result, a network node represents the following devices on the 

M-bus: 

• The network node directly connected to the bus (i.e., itself) 

• All the network nodes existing within the radio network 

• All the radioing meters existing within the radio network 

The number of devices that a network node represents on the M-bus 

can be determined on the basis of the information shown on the LCD 

display (sum of B and C levels). Since most radioing meters only 

possess transmitters but no receivers and since the travel time in the 

radio channel is much greater than the M-bus standard would 

permit, many commands that access the devices are only partly 

executed or are refused (e.g., "Change Cutoff Date"). 


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Building Technologies The Network Node 09.03.2007

3.1 Physical Layer 

Interfaces 

Data can be read out through the following interfaces: 

• Radio 

• M-bus 

• RS232 (WTT16.232 or WTX16.232 only) 

• IrDA (network node firmware version 2.2 and higher) 

The Radio 

Interface 

M-Bus Interface 

In order for the radio interface to be used, a PC equipped with a PC 

radio module (WTZ.RM) and the ACT26 service tool are required. 

This interface is not suited for accessing user-specific readout 

programs and will not be dealt with further in the present material. 

The M-bus interface of the 

WTT16 / WTX16 is an M-bus 

fixed M-Bus connection, 

max. 5 standard load 

slave which conforms to the 

standard, and it features one 

M-bus load. The M-bus 

interface is accessible either 

temporary 

M-Bus connection 

through a temporary plug-in 

MODE 

RESET 

connection or through a 

screwed connection for 

permanent assembly. This interface can only be addressed through 

an M-bus master module. For this, the proper M-bus master, such as 

that of the WTX16.GSM or WTX16.IP, is needed. 

Alternatively, the M-bus interface of the WTT16 / WTX16 can be 

addressed with a PC and a special PC – M-bus adapter, such as the 

WHZ3.USB or WFZ.MBM, and corresponding M-bus master 

software. The M-bus interface of the WTT16 / WTX16 may be 

addressed with 2,400 bauds or 300 bauds. Other baud rates will not 

be accepted. The master recognizes the baud rate automatically. No 

parameterization is required. 

Data are transmitted asynchronously byte by byte. A byte is sent 

with one start bit, eight data bits, one even parity bit and one stop bit. 

There must not be any gap between individual bytes. This means 

that the next start bit has to follow after one or two stop bits. The M- 

bus standard prescribes minimum and maximum response times for 

the M-bus slave. 


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This time interval starts after the telegram has been sent by the 

master. The slave has to sent a reply back to the master within this 

time interval. 

Minimum response delay: 

Maximum response delay: 

11 bit times 

330 bit times + 50 ms 

Reading device data consumes additional current. Therefore, the 

operational life of the battery-powered WTT16 network node is 

shorter than that of other network nodes within the network. For this 

reason, it is recommended that the network node readout through 

the M-bus be limited to one readout per day. If 500 meters are 

stored, this would correspond to an additional battery consumption 

of some 3 %. 

The RS-232 Serial 

Interface 

The RS-232 interface is only 

available in the special 

WTT16.232 and WTX16.232 

models. This interface is 

intended for connecting the 

network node directly to a PC. 

M-bus master software like 

ACT26 may be used for the 

communication with the network node. The data rate is freely 

selectable from 300 bauds to 9,600 bauds and can be set with the 

ACT26 service tool. 

GND 

n.c. 

RTS 

CTS 

Rx 

Tx 

Data are transmitted asynchronously byte by byte. A byte is sent 

with one start bit, eight data bits, one even parity bit and one stop bit. 

There should not be any gaps between individual bytes. Gaps of up 

to 8 milliseconds will be accepted, however. The response times of 

the RS-232 interface are identical to those of the M-bus interface. 

Reading device data consumes additional current. For this reason, 

the operational life of the battery-powered WTT16.RS232 network 

node is shorter than that of other network nodes within the network. 

Therefore, it is recommended that the network node readout through 

the RS-232 interface be limited to one readout per day. If 500 meters 

are stored, this would correspond to an additional battery 

consumption of about 5 %. 


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3.2 Data Link Layer 

Telegram Format 

The M-bus standard supports several telegram formats in 

accordance with [1], Format FT1.2: 

Single 

Character 

Short Frame 

Control 

Frame 

Long 

Frame 

E5h/A2h start 10h start 68h start 68h 

C field L field = 3 L field 

A field L field = 3 L field 

check sum start 68h start 68h 

stop 16h C field C field 

A field 

CI field 

check sum 

stop 16h 

A field 

CI field 

user data 

(0-252 byte) 

check sum 

stop 16h 

Single Character 

Start and Stop 

Symbols 

L Field 

C Field 

A Field 

This format contains one E5h (229d) character and serves to 

acknowledge (CONFIRM) the last successful transmission. Should 

the node detect that more than one of the stored devices are 

addressed, it will send the A2h (162d) character as a negative 

acknowledgement (COLLISION) to signal an apparent collision. 

Through these symbols, the link layer is in a position to recognize 

the beginning and end of a telegram unambiguously. 

The L field describes the length of a telegram. The length 

information takes into consideration all the characters of a telegram, 

excluding start and stop symbols, the check sum and the L field 

itself. The two fields should be identical. Otherwise, the telegram is 

to be discarded. 

The C field (control field) controls the link layer functions of the 

telegram. The C field is based on standard [1]. 

The address field indicates the primary address of the slave that the 

master is communicating with. 


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CI Field 

Check Sum 

Types of M-Bus 

Telegrams 

The CI field (control information field) controls the functions of the 

application layer. Through them, this layer determines the structure 

and significance of the data relayed in the telegram. 

User Data 

The data points relayed in a data structure, together with such 

information as length and type data. This data structure is described 

in greater detail in [3] and consists of a DIB (data information block), 

VIB (value information block) and DATA (value / user data). 

The check sum constitutes the sum (without carry flag) of all the 

bytes transmitted. It is sent for checking the consistency of 

telegrams. 

The table below shows the types of M-bus telegrams (C fields) 

supported by the network node. Any use of C fields not indicated in 

the table will lead to an application error. (See "Application Error.") 

The Annex lists the telegram types as examples. 

Name C Field Binary C Field 

Hex. 

Telegram 

Format 

Description 

SND_NKE 0100 0000 40 Short frame Initialization of slave 

SND_UD 01F1 0011 53/73 Long / control 

frame 

Send user data to slave 

REQ_UD2 01F1 1011 5B/7B Short frame Request for class 2 data 

RSP_UD 0000 1000 08 Long / control 

frame 

Data transfer from slave 

to master after request 

Table 1: Telegram Types (C Fields) Supported by Network Node (F: FCB Bit ) 

Follow-up 

Telegrams (FCB) 

Normalize / Confirm 

Under the M-bus standard [3], large amounts of data can be 

transmitted by means of follow-up telegrams. Follow-up telegrams 

are not supported at the network node. If the Frame Count Valid bit 

(FCV, C Field Bit 4) is set, the Frame Count Bit (FCB, C Field Bit 5) 

will be ignored. 

In the event of primary address and test address agreement or in the 

event of a secondary address, a Normalize telegram (SND_NKE) 

will be acknowledged on a selected device through the E5h 

(CONFIRM) single handshake signal. Whenever a selected device 

receives a Normalize telegram addressed to another device, the 

selection will be cancelled. 


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Send Data / 

Confirm 

Request Data / 

Respond Data 

Commands are transmitted from the master to the slave by means of 

a Send User Data telegram (SND_UD). Every Send User Data 

telegram with a correct primary address, correct secondary address 

or test address will be confirmed through the E5h (CONFIRM) single 

handshake signal. Such confirmation will take place if the telegram is 

received correctly, irrespective of whether the meter knows the data 

or is able to store them (link layer confirmation). Whenever Send 

Data are transmitted with the broadcast address (broadcast; primary 

address = 255), no confirmation will take place. If a response to a 

command is expected, the master needs to perform a request 

(REQ_UD2). 

To receive data from an M-bus slave, the master must retrieve the 

data after a command through a special request. Only then will the 

actual response be transmitted from the slave to the master. 

Of the request telegrams defined in the M-bus standard [3], only 

request user data 2 (REQ_UD2) will be supported by the network 

node. The retrieval of all the information will thus be effected through 

the master. The reply is sent back in the Respond User Data 

telegram (RSP_UD). Request User Data 1 (REQ_UD1) will not be 

processed. However, a CONFIRM will be sent back in response to a 

valid REQ_UD1. 


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M-Bus Protocol 

In reply to a request user data (REQ_UD2), the M-bus slave will 

send a response data telegram (RSP_UD) of the type shown below. 

start character 1 $ 68 not changeable 

telegram length 2 $ 6F length = 111 bytes 

telegram length 3 $ 6F 


c-field 5 $ 08 respond with data 

address field 6 $ AA primary device address (e.g. =170) 

ci-field 7 $ 72 variable structure response 

device 

identification 

8 $ 78 device identification 

device 


device 


device 


9 $ 56 (e.g. 12345678) 

10 $ 34 

11 $ 12 

manufacturer id 12 $ 65 manufacturer (e.g. = 3265h = lse) 

manufacturer id 13 $ 32 

version 14 $ 03 software version (e.g =03) 

medium 15 $ 08 heat cost allocator 

access number 16 $ 1B number of interrogations (e.g. = 27) 

status 17 $ 00 error status (e.g. no error) 

signature byte 1 18 $ 00 no encryption 


variable data 

checksum … $ xx to check bit errors during 

transmission 

stop character … $ 16 not changeable 

Actual data are transmitted with one or several variable length data 

points (in the 'variable data' part). Those data points can be 

transmitted in an arbitrary order, which may change even from one 

transmission to the next. 

Each data point starts with control fields (DIF, DIFE, VIF, VIFE), 

which describe the decryption (length, format, unit, etc.) of the data 

value. A detailed description of these control fields is provided in [3]. 


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Addressing 

Primary Addressing 

Secondary 

Addressing 

The network node supports primary and secondary addressing. 

Primary addresses 0...250 can be assigned to the network node. 

Primary address "0“ is preset by the manufacturer. In addition to the 

assigned primary address, the network node also responds to test 

address 254 and broadcast address 255. The primary address 

always serves to address the M-bus connected network node itself. 

The (virtual) devices stored in it can only be addressed through 

secondary addressing. (See also Page 8.) 

If the master sets the primary address to 253, the slaves will be 

identified through the secondary address. The slave, for its part, will 

respond with the correct primary address (provided that it has a 

primary address). The devices stored in the network node do not 

have any primary address and will equally respond on the M-bus 

with primary address 253. 

The secondary address succeeds the CI field (CI = 72) and is 

always structured as follows: 

Name Format Example 

Device 

4 bytes (BCD) 01234567 

Identification 

Manufacturer 2 bytes (binary) 3265h (12901dez.) = "LSE" 

Code 

Version 1 byte (binary) 01h 

Medium 1 byte (binary) 0Eh 

Table 2: Secondary Address on the M-bus 

The example shown in Table 2 is transmitted on the M-bus in the 

following order: 

67 45 23 01 65 32 01 0E 

Device 

Identification 

The device identification is always given as an 8-digit figure shown in 

binary-coded decimal numbers (BCD). 


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Manufacturer ID 

The manufacturer ID shows the manufacturer's globally unique 

code. The manufacturer ID may be computed from the three letters 

of the manufacturer identifier. The following formula is used for this 

purpose: 

Manufacturer ID = [ASCII(1st letter) – 64] x 32 x 32 

+ [ASCII(2nd letter) – 64] x 32 

+ [ASCII(3rd letter) – 64] 

Siemens Building Technologies electronic (formerly known as Landis 

und Staefa electronic) with the "LSE" identifier thus carries the 

manufacturer ID "12901." 

Version 

Medium 

The version provides the current software version of the device. 

Since the software version is part of the address, a network node will 

change its address following a software update. In other words, 

should a node be given a software update after it had been 

connected to an M-bus master, a new search run needs to be 

performed, so that the master can address this network node again. 

The medium indicates the physical measurand of the device. 

Medium 14 has been set aside for the network node which is not a 

meter. 

Medium 

(decimal) 

Medium 

(hex) Meaning 

00 00 Other 

01 01 Oil 

02 02 Electricity 

03 03 Gas 

04 04 Heat (volume measurement in return pipe ) 

05 05 Steam 

06 06 Hot water (30°C to 90°C) 

07 07 Cold water 

08 08 Heat cost allocator 

09 09 Compressed air 

10 0A Cold (volume measurement in return pipe) 

11 0B Cold (volume measurement in flow pipe) 

12 0C Heat (volume measurement in flow pipe) 

13 0D Heat / cold 

14 0E Network node / system device 

15 0F Unknown 

Table 3: List Showing all the Media Supported in Accordance with [3] 


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Extended 

Secondary 

Addressing 

If the device identification is subsequently changed (e.g., when a 

radio pulse adaptor for water meters is retrofitted), Siemeca devices 

will automatically and additionally broadcast a fabrication number. 

The fabrication number is a copy of the original device ID. It prevents 

any address conflict from occurring on the M-bus (and on the radio 

channel), even if the same device ID has inadvertently been 

programmed in two different devices. The master has to use 

extended selection for that purpose. 

However, if a meter is simultaneously registered in two networks or 

two network nodes from one network are connected to the M-bus, 

there will still be a collision, even if extended selection (without wild 

cards) is used. The reason for such a collision is that the meter is 

simulated on the M-bus by two network nodes. Thus, the same 

device address does, indeed, exist twice on the M-bus. 


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3.3 Application Layer 

Master to Slave 

CI Field (Master) 

Note : 

The following table lists the CI fields which the network node accepts 

from the master. Any CI field other than those given will result in an 

application error. (See Application Error.) 

SND_UD: 

master->slave 

CI Field 

Frame 

Format 

Remark 

application reset 50h control frame 

application select 50h long frame Additional sub code is used for 

selection. 

send data 1) 51h long frame 

selection of slaves 52h long frame 

deselection of 

slaves 

56h long frame 

set baud rate 2) B8h...BDh control frame Not for M-Bus! RS-232 only! 

Table 4: CI Fields Accepted by Network Node 

An acknowledgment (CONFIRM / COLLISION) is sent in response 

to an SND_DU, even if the CI field is not recognized or the 

command is not executed. The acknowledgment applies to 

successful transmission on the link layer only. Any application error 

that may have occurred can be queried through an REQ_UD2. 

The Set Baud Rate command can only be applied to the RS-232. 

The baud rate is automatically switched (300 bauds / 2,400 bauds) 

at the M-bus interface. The command will be ignored. 


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Application Reset / 

Select 

With the aid of Application Reset, the response of the network node 

can be configured for the meters stored. To this end, three groups of 

data may be selected: 

Selected 

Data 

Standard 

Data 

Statistical 

Data 

Tariff 

Data 

Meaning 

Contains current values, cutoff date values and error 

information. 

Contains the consumption of the first measurand at the 

end of each month concerned. 

Contains the consumption of the second measurand at 

the end of each month concerned (water meters only). 

Table 5: Data Groups that May Be Selected at the Network Node for Each Meter Stored 

Whenever an application reset is performed on a meter stored in the 

network node, the standard and statistical data will be configured as 

a standard response. An application reset can also be used to delete 

an application error. 

Application Reset 

(Hex) 

Code 

CI field 1 50 

Application Select 

(Hex) 

Code 

CI Field 1 50 

Sub code for 

application select 

2 30 Example: standard + 

statistical data 


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The following combinations are possible: 

Application Selected Data for Response 

Select 

10 Standard data only 

20 Standard data only 

30 Standard and statistical data 

40 Standard and tariff data 

Other No impact. Application select will be ignored (no 

application error). 

Table 6: Coding for Application Select 

Application Select is stored permanently and preserved until the next 

Application Select or Application Reset is effected. Application 

Select can only be executed on meters. The network node will 

ignore any form of Application Select. 

Send Data 

Send Data is used for transmitting commands to the network node or 

to the devices stored in it. 

Send Data 

(Hex) 

Code 

CI Field 1 51 

DIF 2 01 Example: 

VIF 3 7A 

Value 4 01 

Set primary address to "1." 

Select / Deselect 

The Select command serves to select a specific device on the M-bus 

for communication. "Select" is required only if the slave is to be 

operated through a secondary address. Only one device may be 

selected on the bus at any given time. Otherwise, collisions may be 

caused by slaves responding simultaneously. In such a case, not 

only invalid responses, but also telegrams with a seemingly correct 

content may reach the master, so that deselection will be 

compulsory. Nor may any wildcards be used in the selection 

process, as they are bound to result in multiple selection. 


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Select 

(Hex) 

Code 

CI Field 1 52 

Device ID (4th byte) 2 78 Device ID = 12345678 

Device ID (3rd byte) 3 56 

Device ID (2nd 

byte) 

4 34 

Device ID (1st byte) 5 12 

Manufacturer (2nd 

byte) 

Manufacturer (1st 

byte) 

6 65 Manufacturer ID "LSE" = 12901 

(decimal) 

7 32 

Version 8 01 Software version = 01 

Medium 9 08 Heat cost allocator 

When the communication is finished, the device needs to be 

deselected. Deselection should always take place at the end of any 

given communication and not just when the next communication with 

another device starts. 

There are several ways to deselect a device in the network node: 

• "Deselect" command on the device selected 

• "Select" command on another device 

• SND_NKE on the selected device or another device 

• Change of data rate 

Deselect 

(Hex) 

Code 

CI Field 1 56 



Device ID (2nd byte) 4 34 



byte) 


byte) 

6 65 Manufacturer ID "LSE" = 

12901 (decimal) 

7 32 




Siemens 



Extended Select / 

Deselect 

If the network node identifies a COLLISION following selection 

(without wildcards), a conflict of address may exist. This means that 

the same device ID is used in two meters. In a case of this kind, 

extended selection, which takes the fabrication number into account, 

would be helpful. (See also Page 20.) 

(Hex) 

Extended Select 

Code 

CI Field 1 52 






byte) 


byte) 

6 65 Manufacturer ID "LSE" = 


7 32 



DIF 10 0C 

VIF 11 78 

Device ID (4th byte) 12 32 Fabrication number= 

98765432 


Fabrication 

number(2nd byte) 

14 76 

Fabrication 

number(1st byte) 

15 98 

Set Baud Rate 

Using the CI fields listed in the table, the baud rate can be set at the 

RS-232 interface. Owing to the fact that the baud rate is 

automatically recognized and set, any baud rate setting through the 

M-bus will be ignored. 

CI Field (Hex) B8 B9 BA BB BC BD 

Baud rate 300 600 1200 2400 4800 9600 

Table: Baud Rates Which May Be Set at the RS-232 Interface of the Network Node 


Siemens 



Slave to Master 

CI Field (Slave) 

If the network node has received an REQ_UD2, it will respond with 

an RSP_UD. The table below shows the various responses possible. 

RSP_UD: slave -> 

master 

Report of 

application error 

Respond variable 

data 

CI Field 

70h 

72h 

Frame 

Format 

Long 

frame 

Long 

frame 

Remarks 

Used in case of 

application error 

Standard or command 

response 

Application Error 

If an M-bus master triggers an invalid command on the network 

node, the successful transmission of the command will be 

acknowledged (CONFIRM "E5h"). Together with the next request 

(REQ_UD2), an application error (report of application error) will 

then be sent instead of a normal response (RSP_UD). 

Application Error 

(Hex) 

Code 

CI Field 1 70 

Application error 

code 

2 10 Example 


Siemens 



The following 

application errors 

may occur: 

(Decimal) 

Application 

Error Code 

(Hex) 

Application 

Error Code 

Meaning 

00 00h Non-specified error 

01 01h CI field not supported. 

02 02h Telegram does not fit into input buffer. 

04 04h Premature end of telegram 

05 05h More than 10 DIFEs in a single data point 

06 06h More than 10 VIFEs in a single data point 

08 08h The application is very busy and cannot 

respond at present. 

16 10h Access refused. (User, password or 

authorization invalid.) 

17 11h Command not recognized or supported. 

18 12h Parameter missing or wrong. 

19 13h Unknown receiver address 

Table 7: Application Errors of Network Node The application errors contained in the lines 

highlighted in gray are not listed in [3]. 

The application error may be queried as often as required. However, 

it will be deleted automatically after about four minutes. Also, it will 

be reset by every new command. This way, the standard response 

of the network node can be obtained by an Application Reset prior to 

the Request. 

Standard 

Response of the 

Network Node 

If the network node is sent a Request (REQ_UD2), with no 

command preceding it, the network node will always send back the 

standard response as its response (RSP_UD). 

The standard response to a Request will also be given following a 

command for which no response is generated, but was executed 

without any application error occurring (positive feedback). 

A command, in respect to which a response is expected, will 

produce the command response (RSP_UD) after the Request 

(REQ_UD2) or an application error if the command could not be 

executed successfully. In order to force the standard response of the 

network node, an Application Reset can be requested. 


Siemens 



The response telegram of the network node is always composed of 

an invariable and a variable part and is structured in the following 

manner: (This table shows the application layer only.) 

Standard Response 

(Hex) 

Code 

CI Field 1 72 






byte) 


byte) 

6 65 

7 32 

Version 8 22 

Medium 9 14 

Access number 10 03 

Manufacturer ID "LSE" = 


Software version = 22 

(equivalent to V2.2) 

Network node / system 

device 

Example: Consecutive 

telegram number = 3 

Status 11 04 

Example: Weak battery 

indication 

Signature (2nd byte) 12 00 Encryption always 00 00. 

Signature (1st byte) 13 00 

Variable data.. ... xx Start of variable data 

…. 

xx 

The CI field is followed by an 8-byte secondary address, as 

described in the Secondary Addressing section. 

The Invariable 

Part of the 

Response 

Telegram 

Access Number 

The access number is a consecutive number, which is increased 

with every Request (REQ_UD2). If the value 255 is surpassed, 

numbering will restart at 0. This field ensures that telegrams and 

check sums always change, even if the current meter reading 

remains unchanged. 


Siemens 



Status / Error 

Codes 

The status represents the error status of the network node or the 

error status of the device stored in it. The status is coded in a bit-bybit 

manner. 

Error 

Bit 

0 

1 

(Hex.) 

Value in 

the Event 

of a 

Single 

Error 

00h 

01h 

02h 

03h 

(Decimal) 

Value in 

the Event 

of a 

Single 

Error 

00h 

01h 

02h 

03h 

Meaning 

No error 

Reserved 

Application alert (atypical 

consumption) 

Reserved 

2 04h 04h Weak battery 

3 - - Permanent error (in combination) 

4 - - Minor error (temporary error (in 

5 28h 

combination)) 

Serious device error (permanent 

error) 

6 50h Values measured outside of 

permissible range (temporary error) 

7 88h 

90h 

Communication permanently 

interrupted (permanent error) 

Communication temporarily 

interrupted (temporary error) 

Table 8: Error Codes in Status Field. The lines highlighted in gray are defined by the 

manufacturer (by SBTE in this case). 

Status bits 5, 6 and 7 are always set together with bit 3 or 4. Status 

bit 7 is set by the network node if the connection to the device is 

interrupted. Any attempt by the network node to reestablish the 

connection will be marked as temporary interruption of 

communication. If such attempts remain unsuccessful, the status will 

be converted to permanent interruption of communication. 

Communication errors are displayed with an error date. 

Status bits 5 and 6 are taken over from the device received. Bit 6 

shows a temporary device error, which may correct itself (e.g., 

temperature in flow pipe too high). Bit 5 indicates a permanent 

device error (serious error), which requires servicing in any case 

whatsoever. The exact cause of the error in the malfunctioning 

device can be determined directly on the device by means of a 


Siemens 



service tool. Permanent device errors are transmitted with an error 

date. 

There may even be several errors occurring together. 


Siemens 



Example: 

1. Error code 168 (A8h) indicates a permanent device error and 

permanent interruption of communication at the same time. 

2. Error code 188 (BCh) shows a discharged battery, a permanent 

device error and temporary interruption of communication at the 

same time. 

Signature 

The Variable Part 

of the Response 

Telegram 

Operating Hours 

Example: 

Current Date & 

Time 

Example: 

Albatross ID 

Example: 

In accordance with [3], the signature shows whether and how the 

telegram is encrypted. The encryption on the M-bus is not supported 

in the network node. It is always 00 00. 

The variable data points start after the signature. These may vary as 

a function of the commands given by the M-bus master or as a 

function of the device configuration or the software version. Each 

data point starts with a DIF field. From the DIF or the DIFEs that may 

exist, the lengths of the data point and, with it, the beginning of the 

next data point can be determined. The use of DIF and DIFE control 

fields is explained in the M-bus standard [3]. 

This value shows the number of hours elapsed since the network 

node was started up. 

0C 22 34 12 00 00 

indicates 1,234 operating hours, hence 51 days. 

This data point shows the date and time of the network node. Being 

a type F data point, this data point is encrypted in accordance with 

[3]. 

04h 6Dh 1B 06 CE 06 

corresponds to June 5, 2006, 5:27 a.m. (Standard Winter Time). 

This value provides an unambiguous device type identifier. This 

value is used to ensure the exact identification of devices for service 

tools and does not have to be stored or transmitted for billing 

purposes. 

06 FD 0C 14 00 0E 00 22 03 

is an Albatross ID of the WTT16. 


Siemens 



Device Type (ASN) 

Example: 

Status / Error Date 

Example: 

Network Index 

Example: 

This data point shows the device type. For the network node, the 

device type is either WTT16 or WTX16. Device types are presented 

as a 5-character ASCII string in inverse order. 

0D FD 0B 05 36 31 54 54 57 

shows a WTT16. 

The error date contains a valid value if the meter status indicates a 

permanent device error or temporary or permanent interruption of 

communication. (See also Page 29.) An invalid date is shown with 

FFh FFh. 

32 6C FF FF 

This is not a valid error date. 

For servicing purposes, it is often useful to establish exactly in which 

radio network the network node is located. This data point furnishes 

such information. 

02 FA 3D nn kk 

nn 

kk 

M-bus primary address of the network node through 

which the radioing devices are presented on the M-bus – 

8-bit binary coded 

is the primary radio broadcast address of the node itself. 

The primary radio broadcast address of a network node 

is shown on display level A - 8-bit binary coded. 

Example: 

Main Battery Power 

Consumption 

02 FA 3D 02 0A 

shows network node 10. It forms part of the network that is reached 

through the network node with M-bus primary address 02 on the M- 

bus. 

This data point shows the remaining capacity of the exchangeable 

main battery in percent. Since this consumption cannot be presented 

as a normal M-bus data point, the unit of this value is shown with a 

variable VIF. The unit is ASCII-coded and rendered in inverse order 

according to the M-bus. It shows "% Batt." A 255 consumption value 

signals that the network node concerned is fed externally and not fed 

through a battery. There is no data point for the capacity of the 

backup battery. 


Siemens 



Example: 

01 7C 06 54 54 41 42 20 25 64 

indicates a remaining capacity of 100 percent. 

Since no binding device replacement interval has been set for the 

network node (calibration validity) – as is the case for water meters, 

for instance – the node may be operated up to the end of the battery 

life. 


Siemens 



3.4 Special Network Node 

Commands 

Selection of a 

Device in the 

Memory 

In order to be able to read the addresses of the stored devices, the 

master needs to select the correct position in the memory. The 

memory block and the memory location are required for that. There 

are two memory blocks: 

Memory 

Block 

Memory 

Location 

Explanation 

#1 1..500 Contains the addresses of all the 

meters stored. 

#2 1..12 Contains the addresses of all the 

network nodes stored. 

Table 9: The memory block is selected through special DIFs and DIFEs [3]. 

Memory block #1 (meters): DIF = 42h 

A DIFE is required for memory block #2. 

Memory block #2 (network nodes): DIF=82h DIFE=01h 

The individual device is selected within the memory block through 

the memory location number. 

"Last Memory 

Location" 

Command 

In order for all the devices to be read out efficiently, the occupied 

memory area must be known. Typically, memory occupancy starts 

with memory location 1. This command allows the last memory 

location number used to be read. Various memory locations may not 

be occupied (e.g., when the device has been deleted). For this 

reason, an unused memory location does not signal the end of the 

occupied memory. The command may be applied to memory blocks 

#1 and #2. 

SND_UD #1: 48 FD 22 

SND_UD #2: 88 01 FD 22 

The response to an REQ_UD2 refers to the largest memory location 

used, either for the meter memory (#1) or the network node memory 

(#2). 

RSP_UD #1: 

RSP_UD #2: 

42 FD 22 mp mp 

82 01 FD 22 mp mp 

mp mp 

the largest memory location number used (memory 

position) – (16-bit binary value (unsigned integer)) 


Siemens 



"Read Secondary 

Address" 

Command 

Many devices are stored at one single memory location in the 

network node. This command furnishes the complete secondary 

address for the memory location selected in the event that the 

memory location is used. 

SND_UD #1: 

42 7A mp mp 08 79 

SND_UD #2: 

82 01 7A mp mp 08 79 

The mp mp value constitutes a 16-bit binary value (integer) for the 

identification of the memory location selected. The lowest-value byte 

is transmitted first (LSB first). 

Example: 

42 7A 23 01 08 79 

selects memory location 291 (=123h). 

Depending on the memory block selected, the command provides 

the following responses after an REQ_UD2: 

RSP_UD #1: 

42 7A mp mp 07 79 id id id id ma ma vv mm 

RSP_UD #2: 

82 01 7A mp mp 07 79 id id id id ma ma vv mm 

If there is a secondary address at this memory location, whose 

device ID is different from the fabrication number, the following 

response will appear: 

RSP_UD #1: 

42 7A mp mp 07 79 id id id id ma ma vv mm 0C 78 fn fn fn fn 

RSP_UD #2: 

82 01 7A mp mp 07 79 id id id id ma ma vv mm 0C 78 fn fn fn fn 

mp mp queried memory location number (memory position) – 

(16-bit binary value (unsigned integer)) 

id id id id Device ID – 32-bit (8-digit) BCD-coded 

ma ma Manufacturer code – 16-bit binary value (unsigned 

integer) 

vv Version – 8-bit binary value (unsigned integer) 

mm Medium – 8-bit binary value (unsigned integer) 


Siemens 



Example: 

RSP_UD: 42 7A 23 01 07 79 78 56 34 12 65 32 14 0E 0C 78 32 54 

76 98 

Memory block #1 (DIF = 42) 

Memory position 

291 (123h) 

Device ID 12345678 

Manufacturer ID 

LSE (3265h) 

Version 

20 (14h) 

Medium 

14 (0Eh) 

In the response, too, the lowest-value byte is transmitted first (LSB 

first). 

If the memory location is not used or if the memory location number 

selected is invalid, only a shortened response will come up: 

RSP_UD #1: 

42 7A mp mp 

RSP_UD #2: 

82 01 7A mp mp 

mp mp queried memory location number (memory position) – 

(16-bit binary value (unsigned integer)) 

Search Run und 

Readout of an M- 

bus with Network 

Node 

Search Run of 

Primary-address 

Devices 

In order for an M-bus master to communicate with an M-bus slave, 

the master must know the address of the device. To this end, it must 

learn in all the available devices on the M-bus when it is first started. 

The master uses different approaches for primary-address and 

secondary-address devices. 

A total 251 M-bus slaves may be connected to an M-bus line. 

1. Accessing test address 254 with SND_NKE 

a. If no response has been received within the 

maximum response delay, there are no devices on 

the M-bus. (The master should repeat the test.) 

b. If exactly one CONFIRM has been received within 

the maximum response delay, there is only one 

device on the M-bus. The master sends an 

REQ_UD2 to read out the device data. 


Siemens 



c. If more than one CONFIRM or something else has 

been received as CONFIRM, there is more than one 

user on the M-bus. The primary search run is started. 

2. Commencing with address 0, an SND_NKE is sent to each 

primary address. The next address will not be called up until 

the maximum response delay has elapsed. 

a. If a CONFIRM is received, the master will send an 

REQ_UD2 to the valid primary address to read out 

the device data. 

b. If several CONFIRMs or something else are received, 

the test at this address should be repeated. If the 

result proves to be the same, two devices have been 

programmed with the same primary address. An alert 

or an error message should be issued. After that, the 

search run is to be continued. 

The primary search run may be shortened by the user predefining 

the maximum number of M-bus devices. 

Search Run of 

Secondary-address 

Devices (Wildcard 

Search) 

The devices stored in the network node cannot be accessed by 

primary addressing. If this is the case, the master will resort to the 

wildcard search described in [3]. Under this method, the master will 

use wildcards for parts of the address which are accepted by every 

M-bus slave. Depending on the result – i.e., whether none, one or 

several devices respond – the address will be broken down further. 

As wildcard symbol, "F" is used in BCD-coded parts of the address, 

while "FFh" is used in binary-coded parts of the address. 

Example: 

The following network nodes are connected on an M-bus. But only 

the network nodes "selected" respond to a "Select" sent to address 

FF 0F 00 10 65 32 FF 0E (LSB first). 

Device ID 

Manufactur 

er ID 

Version Medium Response 

to a Select 

10000001 LSE 20d 14d Yes 

10000987 LSE 20d 14d Yes 

10001001 LSE 20d 14d No 

10000001 LSE 21d 14d Yes 

10000001 LSE 20d 15d No 


Siemens 



Readout of Device 

List from Network 


The wildcard search will take the longer, the more users there are on 

the M-bus. Since a network node may represent up to 500 devices 

and 12 network nodes on the M-bus and several network nodes 

(from different networks) may be connected to the M-bus, a wildcard 

search would possibly take many hours to complete. For this reason, 

another method for learning in devices has been implemented in 

version 1.4 and higher. 

1. A primary search run is carried out. In this run, all the devices 

with unambiguous primary addresses will be found. 

2. The M-bus devices recognized must be identified as network 

nodes. For this purpose, the secondary address of each M-bus 

device found is checked. Each of the following conditions have 

to be met: 

a. Manufacturer must be LSE (3265h or 12901). 

b. Version must be higher or equal to 0Eh (or 14d). 

c. Medium must be equal to 0EH (or 14d). 

3. The following procedure is applied to each network node 

identified: 

a. Select network node. 

b. Send Last Memory Location command (memory 

block #1) to the primary address of the network node 

and wait for CONFIRM. 

c. Send REQ_UD2. The response will contain the last 

valid memory location. 

d. Send Read Secondary Address command to memory 

location 1 and wait for CONFIRM. 

e. Send REQ_UD2. The response contains the 

secondary address of the device at memory 

location 1. This address will be stored in the device 

list of the master. 

f. Using a memory location number increased by 1 in 

each case, repeat steps d. and e. until the last valid 

memory location has been read out. 

g. If network node information is to be read out as well, 

steps b. through f. also need to be repeated for 

memory block #2. 


Siemens 



h. Now, the master possesses a complete list of all the 

devices of this network node. The network node is to 

be deselected. 

4. Once the secondary addresses of all the stored devices have 

been read out and stored in the device list, the M-bus master 

will start the read-out process. 

a. To this end, every device registered in the device list 

is to be selected. 

b. Using an REQ_UD2, the current data of the devices 

are queried. 

c. The device is to be deselected thereafter. (This may 

also be done by selecting the next device.) 

5. Now, the data of the devices not recognized as network nodes 

under step 2. should be read out as well. 

6. In conclusion, the bus is to be reset by an SND_NKE sent to 

the primary address of a network node. 

The disadvantage of the procedure described above is that only 

primary-address M-bus devices and the radioing meters stored will 

be found. Correct M-bus devices, which do not support primary 

addressing, will only be found through a wildcard search. The same 

applies to situations in which more than one M-bus device is 

employed and where the primary address is permanently 

programmed to 0 and cannot be changed. Collisions on primary 

address 0 can only be prevented by using the secondary address or 

by switching off competing devices. 


Siemens 



4 Meters 

Memory Block 

(storage number) 

Not only does each meter transmit the current consumption reading, 

it also relays the consumption at predefined times. As a 

consequence, there are several dates and numerous consumption 

values. In order for them to be presented in the right context, the 

data points belonging together use the same memory block number 

(storage number. 

Memory Meaning 

Block 

#0 Current consumption 

#0 Current status and device information 

#1 Consumption at cutoff date 

#8..#25 Statistics (consumption at end of month) 

Table 10: Use of Memory Blocks in Meters 

It should be noted that meters do not switch from Standard Summer 

Time to Standard Winter Time and back. Therefore, a one-hour 

difference to real time may occur even in new devices. 


Siemens 


Building Technologies Meters 09.03.2007

4.1 Current Data (Memory Block #0) 

The Annex lists an example of communication between the meter 

and the M-bus master for all the data points presented. 

Albatross ID 

Example: 

Network Index 

This value provides an unambiguous device type identifier. This 

value is used by service tools and need not be stored or transmitted 

for billing purposes. 

06 FD 0C 2B 00 07 00 5D 02 is the Albatros ID of the WFM36. 

For servicing purposes, it will be helpful to find out in which radio 

network the meter is received. This data point furnishes such 

information. 

02 FA 3D nn kk 

nn 

kk 

M-bus primary address of the network node through 

which the meter is represented on the M-bus – 8-bit 

binary coded 

is the primary radio broadcast address of the node that 

receives the meter directly and transmits its data. The 

primary radio broadcast address of a network node is 

shown on display level A - 8-bit binary coded. 

Example: 

02 FA 3D 02 0A 

shows that the meter is received by network node 10 and distributed 

in the network. The network node carrying M-bus primary address 

02 presents the meter on the M-bus. 

Current Date & 

Time 

Example: 

Current 

Consumption 

This data point shows the time when the consumption data are 

generated in the meter and sent off. As running time in the radio 

network may stretch over several days (or be considerably longer in 

the event of an error), the current date and time of the meter are 

perceptibly different from the actual readout time. Being a type F 

data point, this data point is encrypted in accordance with [3]. 

04 h6 Dh 1B 06 CE 06 

corresponds to June 5, 2006, 5:27 a.m. (Standard Winter Time). 

This value shows the current consumption at the current date. 


Siemens 



Example: 

Leakage Duration 

Example: 

Status / Error Date 

Example: 

0C 13 35 00 00 00 

shows a current consumption of 35 liters. 

In selected volume meters, such as WFx36 water meters, leakage 

duration is transmitted as well. This current value is given in hours 

and describes the period since when water has been consumed 

without any interruption (e.g., in the event of a defective toilet 

flushing mechanism). When leakage duration exceeds a predefined 

limit, an additional application alert will be transmitted in the status 

message. (See Page 29.) 

02 BB 56 05 00 

shows that consumption has been uninterrupted for five hours. 

The error date contains a valid value when the meter status 

indicates a permanent device error or temporary or permanent 

interruption of communication. (See also "Status / Error Codes" on 

Page 29.) An invalid date is presented with FFh FFh. 

32 6C FF FF This is no valid error date. 


Siemens 



4.2 Cutoff Date Data (Memory 

Block #1) 

Cutoff Date 

Example: 

The cutoff date shows the end of a billing period and is usually set to 

December 31 of each year. It can be changed directly on the meter 

by means of service tools. The cutoff date is presented with memory 

block #1. If no cutoff date has been reached yet, either 

FF FF ("x x x") or FF FC ("31.12.--") will be transmitted. 

42 6C DE 04 

shows the most recent cutoff date in relation to April 30, 2006. 

42 6C FF FC 

shows that the next cutoff date has been preprogrammed for 

December 31. But no cutoff date has been exceeded yet. (Cutoff 

date is still invalid.) 

Consumption at 

Cutoff Date 

This value shows the consumption of the meter at the end of a given 

cutoff date. If no cutoff date has been exceeded yet, "0" 

consumption will be transmitted. There are two consumption values 

at the cutoff date for heat meters or heat / cold meters. 

Heat Meters (Medium 04d) 

• Heat energy consumption marked as tariff 0 

• Volume consumed marked as tariff 0 

Example: 

4C 04 34 12 00 00 

shows a consumption of 12.34 kWh, while 

4C 13 23 01 00 00 

shows a consumption of 123 liters. 

Heat / Cold Meters (Medium 13d) 

• Heat energy consumption marked as tariff 0 

• Cold energy consumption marked as tariff 1 

Example: 

4C 04 34 12 00 00 

shows a (heat) consumption of 12.34 kWh, while 

CC 10 04 23 01 00 00 

shows a (cold) consumption of 1.23 kWh. 


Siemens 



4.3 Statistical Data 

(Memory Block ≥ #8) 

Statistics 

At the beginning of the subsequent month, the network node will 

receive the consumption of the meter at the last day of the preceding 

month (end-of-month value). This value is stored in the network 

node. The network node is capable of storing 13 end-of-month 

values (up to version 1.4) or 18 end-of-month values (version 2.0 

and higher). End-of-month values are stored as statistical values. 

Statistics always start on memory block #8. It is there that the oldest 

value is stored. The statistical value stored most recently is found at 

the highest memory location number. When all the memory locations 

are occupied, the oldest value is discarded. The second oldest value 

is stored in memory block #8, with the third oldest kept in memory 

block #9 and so on. The most recent statistical value is stored in the 

highest memory block (#25 in version 2.0 and higher and #20 up to 

version 1.4). In the event that a statistical value could not be 

transmitted due to radio interference, a gap will be left when the next 

statistical value is transmitted. The value that could not be 

transmitted will be filled with FF. 

Example: 

Description 

DIF/DIFE 

(Hex) 

VIF/VIFE 

(Hex) 

(Hex) Value 

(Example) 

Number of memory 

blocks transmitted 

89 04 FD 22 03 

Date of most recent 

memory block 

82 05 

(memory 

block #10) 

6C DF 05 

Time gap between 

memory blocks 

(always one month) 

89 04 FD 28 01 

Memory block #10 8C 05 13 23 01 00 00 

Memory block #9 

(transmission error) 

CC 04 13 FF FF FF FF 

Memory block #8 8C 04 13 95 00 00 00 


Siemens 



The example shows the statistical values of a water meter, which 

was read out from the network node three months after its 

installation. 

The following consumption values can be obtained from the 

statistical data points of the above example: 

Date 

Last end-of-month value May 31, 

2006 

Value 

123 liters (10 -3 m 3 ) 

Second (penultimate) endof-month 

value 

April 30, 

2006 

x x x (invalid) 

First end-of-month value March 31, 

2006 

95 liters (10 -3 m 3 ) 

4.4 Overview of Data Points for 

Siemeca Meter Statistics 

A broadsheet (see [6]) provides an overview of the data points 

supported by Siemeca devices. 


Siemens 



5 Annex 

5.1 M-Bus Ranges 

The table below serves as a general guideline for the ranges achievable with the M-bus. However, the properties of the specif 

especially those of the M-bus master, need to be considered as well. The following calculation example is based on an M-bus 

with an WZC.P250 level converter. If WZC.P250s are connected in series, the maximum cable length will increase accordingl 

Type of System 

Small Residential 

Buildings 

Larger Residential 

Buildings 

Smaller 

Neighborhoods 

Larger 

Neighborhoods 

Maximum 

Distance 

Cumulative Cable 

Length 

Diameter or Cross-section of 

Cable 

Number of M-Bus 

Devices (Slaves) 

350 m 1,000 m 0.8 mm 250 9,6 

350 m 4,000 m 0.8 mm 

250 2,4 

64 9,6 

1,000 m 4,000 m 0.8 mm 64 2,4 

3,000 m 5,000 m 1.5 mm 64 2,4 

Ma 

Tra

5.2 Types of M-Bus Telegrams 

Note: $00 means a hexadecimal number. 

req_ud2 

Cod 

e 

start character 1 $ 10 

c-field 2 $ 5b request for data 

with fcb=0 (or $7b with 

fcb=1) 

address field 3 $ aa device address = 170 

checksum 4 $ 05 

stop character 5 $ 16 

RSP_UD 


telegram length 2 $ 6f length = 111 bytes 

telegram length 3 $ 6f 


c-field 5 $ 08 respond with data 

address field 6 $ aa primary device address (e.g. 

=170) 

ci-field 7 $ 72 variable structure response 

device identification 8 $ 78 device identification 

device identification 9 $ 56 (e.g. 12345678) 

device identification 10 $ 34 

device identification 11 $ 12 

manufacturer id 12 $ 65 manufacturer (e.g. = 3265h = 

lse) 

manufacturer id 13 $ 32 

version 14 $ 03 software version (e.g =03) 

medium 15 $ 08 heat cost allocator 

access number 16 $ 1b number of interrogations (e.g. 

= 27) 

status 17 $ 00 error status (e.g., no error) 



variable data 

checksum … $ xx to check bit errors during 

transmission 

stop character … $ 16 not changeable 


Siemens 


Building Technologies Annex 09.03.2007

SND_UD 

start character 1 $ 

68 

telegram length 2 $ 

08 

telegram length 3 $ 

08 

start character 4 $ 

68 

c-field 5 $ 

53 

address field 6 $ 

aa 

ci-field 7 $ 

51 

variable data … x x 

... x x 

checksum 

x x 

stop character last $ 

16 

confirm 

acknowledgement byte 

length 

send user data; fcb=0 (7 3 

fcb = 1) 

device address = e.g., 170 

data send 

$ e5 


Siemens 



5.3 Meter Readout from Network 


The following is an example of communication between the 5750010 

water meter and the M-bus master. 

Master: SELECT 68 0B 0B 68 73 FD 52 10 00 

75 05 65 32 2B 07 15 16 

Slave: CONFIRM E5 

Master: REQ_UD2 10 7B FD 78 16 

Slave: 

RSP_UD2 

DLL header 68 5B 5B 68 08 FD 

APL header 72 10 00 75 05 65 32 2B 07 

04 00 00 00 

Albatros ID 06 FD 0C 2B 00 07 00 5D 02 

Network index 02 FA 3D 02 0A 

Current date 04 6D 1B 06 CE 06 

Current 

0C 13 35 00 00 00 

consumption 

Cutoff date 

42 6C FF FC 

Consumption at 4C 13 00 00 00 00 

cutoff date 

Error date 

32 6C FF FF 

Statistical length 89 04 FD 22 03 

Statistical date 82 05 6C DF 05 

(#10) 

Statistical interval 89 04 FD 28 01 

Memory block 8C 05 13 23 01 00 00 

#10 

Memory block #9 CC 04 13 FF FF FF FF 

Memory block #8 8C 04 13 95 00 00 00 

Check sum + D3 16 

postamble 

Master: SND_NKE 10 40 FD 3D 16 

Slave: CONFIRM E5 


Siemens 




Siemens 



Keyword Index 

A 

A Field..............................................................................................17 

Addressing...........................................................................20, 23, 32 

Albatross ID ...............................................................................36, 48 

Application Error ............................................................17, 24, 30, 31 

Application layer ................................................................................9 

Application Layer 

Standardantwort vom Netzwerkknoten........................................34 

Application Layer .........................................................................3, 24 

Application Reset / Select................................................................25 

C 

C Field .......................................................................................16, 17 

Check Sum ......................................................................................17 

CI Field ..................................................17, 24, 25, 26, 27, 29, 30, 32 

Current Consumption.......................................................................49 

Current Date & Time..................................................................36, 48 

Cutoff Date.............................................................................3, 12, 51 

D 

Data link layer ....................................................................................9 

Data Link Layer............................................................................3, 16 

Device Identification.........................................................................20 

Device Type.....................................................................................37 

F 

Follow-up Telegrams .......................................................................17 

Follow-up Telegrams (FCB).............................................................17 

I 

Invariable Part of the Response Telegram ......................................33 

L 

L Field ..............................................................................................16 

Last Memory Location ...............................................................39, 45 

Leakage Duration ............................................................................50 

M 

Main Battery Power Consumption ...................................................37 

Manufacturer ID ...........................................21, 27, 28, 29, 32, 43, 44 

M-Bus Addressing .............................................................................7 

M-Bus Data Transmission Format.....................................................7 


Siemens 


Building Technologies Keyword Index 09.03.2007

M-Bus Interface ...............................................................................13 

M-Bus Protocol ................................................................................19 

M-Bus Range.....................................................................................6 

M-Bus Standard.................................................................................9 

M-Bus Topology.................................................................................6 

Medium ............................8, 20, 21, 27, 28, 29, 32, 42, 43, 44, 45, 51 

Memory Block......................................................3, 39, 47, 48, 51, 52 

N 

Network Index............................................................................37, 48 

Network Node ..................................................................................11 

Network Node Commands...........................................................3, 39 

Normalize / Confirm .........................................................................17 

O 

Operating Hours ..............................................................................36 

OSI Reference Model ........................................................................9 

P 

Physical layer.....................................................................................9 

Physical Layer .............................................................................3, 13 

Primary Address ................................................................................7 

R 

Radio Interface ................................................................................13 

Read Secondary Address..........................................................41, 45 

Readout of Device List from Network Node ....................................45 

Request Data / Respond Data.........................................................18 

RS-232 Serial Interface ...................................................................15 

S 

Search Run of Primary-address Devices ........................................43 

Search Run of Secondary-address Devices (Wildcard Search)......44 

Secondary Address ...........................................................................8 

Select / Deselect........................................................................26, 29 

Selection of a Device in the Memory ...............................................39 

Send Data..................................................................................18, 26 

Send Data / Confirm ........................................................................18 

Set Baud Rate ...........................................................................24, 29 

Signature ...................................................................................32, 36 

Single Character ..............................................................................16 

Standard Response...................................................................31, 32 

Start and Stop Symbols...................................................................16 

Statistics ..........................................................................3, 47, 52, 53 

Status / Error Date.....................................................................37, 50 


Siemens 



T 

Telegram Format .......................................................................16, 17 

Types of M-Bus Telegrams....................................................3, 17, 56 

V 

Variable Part of the Response Telegram ........................................36 

Version...................................8, 20, 21, 27, 28, 29, 32, 41, 43, 44, 45 


Siemens 




Siemens 



This documentation only provides general descriptions and/or performance characteristics, which, 

in a given case, may not always apply in the manner presented or may change as products evolve. 

Desired performance characteristics shall only be binding if expressly agreed in the relevant 

contract signed. 

Siemens 

Building Technologies electronic GmbH 

HVP-IP 

Sondershäuser Landstr. 27 

99974 Mühlhausen/Thüringen 

Germany 

Tel: +49 (3601) 46 83-0 

Fax: +49 (3601) 46 83-34 

www.siemens.com/siemeca 

2006 Siemens Building Technologies AG 

Subject to change 


Siemens 

Building Technologies 


Keyword Index 

09.03.2007 

Återförsäljare: 

ARMATEC AB 

Box 9047 

SE_400 91 Göteborg, SWEDEN

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