1 INTRODUCTION Seite 2

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1 1 INTRODUCTION COMMUNICATION INTERFACES COMMUNICATION PRIORITIES TELEGRAM FORMATS UART Baud rates Parity detection PROTOCOL LAYER CONNECTION SET-UP FOR OPTICAL ZVEI CONNECTION SET-UP FOR M-BUS METER CONFIGURATION NEW PRIMARY ADDRESS NEW READING DATE WRITING THE RAM TEST COMMANDS ADDRESSING Primary address Secondary address Selection Deselection TELEGRAM PROTOCOLS READING THE METER Requesting standard response RAM read Special codes in values METER TELEGRAM METER TELEGRAM 2 (RAM)...10 Seite 2

2 1 Introduction The M-Bus (Meter Bus) is a European standard for remote reading of meters. It can be used for all types of supply meters and for various sensors and actuators. This document does not deal with the M-Bus protocol in detail. Further information can be found on the Internet at The application layer of the M-Bus protocol is also used for the optical interfaces and the L-Bus interface of this water meter. 2 Communication Interfaces The water meter is available in two versions. Depending on the version it is equipped with several communication interfaces: Optical ZVEI: a light pulse (or a missing pulse) represents a single bit. M-Bus: a two-wire bus, polarity does not matter. The bus voltage is about 40 VDC, the meter is supplied by the bus when connected. L-Bus: a two-wire bus with a bus voltage of about 3,6 VDC. The meters output is open collector and has to be connected with the right polarity. The meter is not supplied by the L- Bus Interface Combinations depending on module version Interface MBus/LBus/Pulse MBus/Pulse M-Bus L-Bus 1) optical ZVEI pulse output forward volume 1) pulse output forward and reverse volume 1) 1) The L-Bus and the pulse output(s) are available only on water meters that have been equipped with a 5-pole cable during manufacture. 2.1 Communication priorities Mutual influence between interfaces: Interface Priority M-Bus 1 Optical ZVEI 2 Once the M-Bus is connected, the optical ZVEI interface can no longer be used. Any communication in progress over the ZVEI interface is re-routed to the M-Bus when the M-Bus is detected. Modules with L-Bus interface do not have a ZVEI interface. 2.2 Telegram formats Communication complies with: IEC Telecontrol equipment and systems; Transmission protocols; Section One - Transmission frame formats. Seite 3

3 2.3 UART Baud rates M-Bus/L-Bus: 300 and 2400 bauds (300 bauds: transmission in Interrupt Mode) Baud rate switching: automatic ZVEI optical: 2400 bauds Parity detection according to IEC (even parity) 2.4 Protocol layer 1. IEC corresponding to EN Data output (RSP_UD) a) Variable protocol b) Least Significant Byte first (Mode 1) for multi-byte variables c) All response telegrams also available for C1 errors 2.5 Connection set-up for optical ZVEI To activate the optical ZVEI interface, a 0-1 bit pattern must be sent at 2400 bauds for 2.2 s (= 480 bytes $55 8 data bits No parity 1 stop bit). The actual communication can be started after a pause of 11 to 330 bit times (2400 bauds). The optical interface disables itself by means of a timeout counter if not used. This counter is decremented by 1 every 250 ms (4 Hz) and disables the optical interface on reaching Connection set-up for M-Bus After connection to the M-Bus, the TSS 721 interface module needs ma. 590 ms before it is ready for reliable communication. => A wait time of 590 ms must be observed between connection of the M-Bus and the start of communication. Seite 4

4 3 Meter configuration The meter configuration is always based on a long frame with the following structure: Byte Bedeutung Erklärung/Inhalt/Wert Header Long Frame (HLF) HLF 1 1. start character $68 HLF 2 length field 3 + HLF 3 length field 3 + HLF 4 2. start character $68 HLF 5 C-field $53/$73 SND_UD HLF 6 A-field (Bus) address of the meter HLF 7 CI-field $51 data send Mode 1 Variable Data Blocks (VDB) VDB 1.. VDB end of LongFrame (ALF) ALF 1 checksum ALF 2 stop character $16 Correct communication is partly dependent on the status of the PLEV-bit. This indicates the write protection status: PLEV-bit Status 0 No write protection 1 Partial write protection, all test commands possible 2 Write protection, future reading date and primary address possible 3 Full write protection 3.1 New primary address If VBD1 = $01 and VDB2 = $7A, VDB3 is used as new primary address. Attention: The primary address can only be changed if PLEV-bit is < 3. Eample (address 233): $68 $06 $06 $68 $53 $FE $51 $01 $7A $E9 $06 $ New reading date If VBD1 = $42, VDB2 = $EC and VDB3 = $7E, VDB4 and VDB5 are used as new future reading date (data type G). Attention: PLEV-bit must be < 3. The meter can be configured in production so that the reading date can only be changed once. Eample ( ): $68 $08 $08 $68 $53 $FE $51 $42 $EC $7E $5F $CC $79 $ Writing the RAM Only possible in production! Seite 5

5 4 Test commands Protocol structure: Byte Bedeutung Erklärung/Inhalt/Wert Header Long Frame (HLF) HLF 1 1. start character $68 HLF 2 length field $06 HLF 3 length field $06 HLF 4 2. start character $68 HLF 5 C-field $53/$73 SND_UD HLF 6 A-field (Bus) address of the meter HLF 7 CI-field $51 data send Mode 1 Variable Data Blocks (VDB) VDB 1 DIF $2F ("Idle Filler" for SW-UART) VDB 2 DIF = MDH $0F proprietary data until end VDB 3 HY - FC Hydrometer specific functioncode end of LongFrame (ALF) ALF 1 checksum ALF 2 end character $16 Hydrometer-specific function codes: HY-FC HY-FC Function Description PLEV Data $00 - PLEV down decrement protection level 1,3 $01 - PLEV up increment protection level 0-2 $02 - Start volume calibration $03 - Stop volume calibration $04 - button simulates pressing button 4.1 Addressing The meter can be addressed using two addressing variants: with a logic address (primary address) or by using a filter via its e works identification (secondary address) Primary address The A-field is assigned the bus address for communication. This bus address must only eist once for each system and must accordingly be issued for a specific system. This method of addressing is not recommended for larger bus systems due to this time-consuming address handling. Special cases: A-field Function Use $FD Characters for secondary addressing Secondary addressing $FE Broadcast (to all) with response Only one meter connected $FF Broadcast (to all) without response System-wide control Secondary address Secondary addressing is based on the system of dynamic assignment of the primary address $FD. This assignment of which meter is to respond to the primary address $FD is made using a selection telegram to the primary address $FD. A selection already made can be cancelled using a stop filter or a deselection telegram. Seite 6

6 Selection Request telegram: 68 0B 0B FD 52 NN NN NN NN HH HH ID MM CS 16 Response: E5 (only if filter matches) Structure of filter: 4 bytes NNUM BCD NN (serial number) $F digit joker 2 bytes HST HH (manufacturer s code) $FF byte joker 1 byte ID (here: $26) ID (ident. code) $FF joker 1 byte SMED MM (medium code) $FF joker After selection, the meter behaves as if it had the primary address $FD and can therefore be operated via the primary address $FD Deselection Request telegram: FD CS 16 Response: E5 To reliably end communication with the selected meter, the meter must be deselected. The primary address $FD then becomes free again and can be used for communication with another meter. Seite 7

7 5 Telegram protocols Name C - Feld CI - Feld Beschreibung Antwort SND_NKE $40 - communication reset $E5 SND_UD $53/$73 $51 send data mode1 $E5 $52 selection only if A - field = $FD REQ_UD1 $5A - request class 1 data, time critical data. Not implemented, answer is always $E5 (which means no alarm) $E5 $E5 REQ_SKE $49 - status request RSP_SKE (10 4B 01 4C 16) REQ_UD2 $5B, $7B - request class 2 data Response telegram 1 (standard) or response telegram 2 when sending APP_RES with subcode $B0 before REQ_UD2 APP_RES $53/$73 $50 application reset, subcode $00 for response telegram 1 and subcode $B0 for response telegram 2 $E5 5.1 Reading the meter Display: AA = A-field CS = Checksum all values in he LL = Long field Requesting standard response request telegramm REQ_UD2 10 7B AA CS 16 or 10 5B AA CS 16 response response telegram RAM read request telegramm response APP_RES B FE 50 B E5 REQ_UD2 10 7B AA CS 16 or 10 5B AA CS 16 response telegram 2 Attention: after sending APP_RES B0 the meter stays in mode "response telegram 2 after REQ_UD2" for a maimum of 5 minutes. Then the standard response (response telegram 1) is send again. To get telegram 1 again immediately, an APP_RES with subcode $00 can be send before REQ_UD Special codes in values The character B stands for F The character D stands for space The character F stands for - sign Eample: BF4D: F-4 F0023: Seite 8

8 5.2 Meter telegram 1 Telegram 1 all user-relevant data of the meter: (1) Current accumulated volume, the most significant 4 bytes (BCD) (2) High resolution volume, 4 bytes, factor 100 more accurate than (1). (3) Current flow (4) Current forward volume (5) Current reverse volume (6) Current time and date (7) Volume at account day (8) Date of account day Byte number Byte name Meaning Description/content/value Header Long Frame (HLF) 1 HLF 1 1st start character $68 2 HLF 2 Long field $40 (3+ 12 FDB + 49 VDB) 3 HLF 3 Long field $40 4 HLF 4 2nd start character $68 5 HLF 5 C-field $08 RSP_UD 6 HLF 6 A-field (Bus) address of meter 7 HLF 7 CI-field $72 variable response mode 1 Fied Data Block (FDB) 8 11 FDB 1 - FDB 4 ID number equipment identification number 8-digit BCD 12 FDB 5 Manufacturer ID e.g. $2324 = HYD 13 FDB 6 14 FDB 7 Generation of meter Software-ID = $3A 15 FDB 8 Measured media $07 for water, $06 for hot water 16 FDB 9 Access number transmission counter 17 FDB 10 Status see standard FDB Signature $0000 = unencrypted Variable Data Blocks (VDB) 20 VDB DIF1 $0C = currently 8 digit BCD 21 VDB VIF1 current volume ($15 = 0,1 m 3 = 100Liters) VDB Value Record 1 current volume 26 VDB DIF2 $8C = currently 8 digit BCD, DIFE follows 27 VDB DIFE $10 tariff = 1 28 VDB VIF2 current volume ($13 = 1 Liter) VDB Value Record 2 current high resolution Volume 33 VDB DIF3 $0c =currently 8 digit BCD 34 VDB VIF3 $3B = flow [l/h] VDB Value Record 3 current flow 39 VDB DIF4 $8C = currently 8 digit BCD, DIFE follows 40 VDB DIFE $20 tariff = 2 41 VDB VIF4 volume ($15 = 0,1m 3 ) VDB Value Record 4 current forward volume 46 VDB DIF5 $8C = currently 8 digit BCD, DIFE follows 47 VDB DIFE $30 tariff = 3 48 VDB VIF5 volume ($15 = 0,1m 3 ) VDB Value Record 5 current reverse volume 53 VDB DIF6 $04 = currently 32 Bit Integer 54 VDB VIF6 $6D = time & date datatype F VDB Value Record 6 current time & date 59 VDB DIF7 $4C = 1. storage value 8 digit BCD 60 VDB VIF7 current volume ($15 = 0,1m 3 ) VDB Value Record 7 last account day's volume 65 VDB DIF8 $42 = 1. storagevalue 16 Bit Integer 66 VDB VIF8 $6C = timepoint Data Type G VDB Value Record 8 account date end of LongFrame (ALF) Seite 9

9 69 ALF checksum $ 70 ALF end character $ Meter telegram 2 (RAM) Byte number Byte name Meaning Description/content/value Header Long Frame (HLF) 1 HLF 1 1. start character $68 2 HLF 2 length field $yy (3 + FDB RAM + 1) 3 HLF 3 length field $yy 4 HLF 4 2. start character $68 5 HLF 5 C-field $08 RSP_UD 6 HLF 6 A-field (Bus) Adresse des Zählers 7 HLF 7 CI-field $72 variable Antwort Mode 1 Fied Data Block (FDB) 8 11 FDB 1 - FDB 4 IDnumber equipment identification number 8-stellig BCD 12 FDB 5 manufacturer ID e.g. $2324 = HYD 13 FDB 6 14 FDB 7 generation of meter software-id = $3A 15 FDB 8 devicetype (measured media) $07 for water, $06 for hot water 16 FDB 9 access number transmission counter 17 FDB 10 status see standard FDB signature $0000 = unencrypted Variable Data Blocks (VDB) 20 VDB DIF $0F = manufacturer specific data follows RAM 1 RAM end of LongFrame (ALF) 254 ALF 1 checksum 255 ALF 2 end character $16 Seite 10