Protocol; Commands; The Individual Commands In Detail; M-Bus Master To M-Bus Slave - Kamstrup M-Bus Technical Description

11. Protocol

Commands

The M-Bus concept includes the possibility of
various commands from M-Bus Master to M-Bus
Slave and from M-Bus Slave to M-Bus Master.
For the Kamstrup M-Bus system certain commands
which are relevant for the communication with a
district heat meter have been chosen.

M-Bus Master to M-Bus Slave:

REQ_UD2 Collects data from
the M-Bus Slave
SND_NKE Initiates the M-Bus Slave
SND_UD1 Send data to M-Bus Slave,
e.g. new baudrate
M-Bus Master to M-Bus Slave
REQ_UD2: Collect data from M-Bus Slave
STARTCHARACTER 10H
C-FIELD 5BH
A-FIELD XXH
CHECKSUM XXH
STOPCHARACTER 16H
SND_NKE: Initiate M-Bus Slave.
STARTCHARACTER 10H
C-FIELD 40H
A-FIELD XXH
CHECKSUM XXH
STOPCHARACTER 16H
SND_UD1: Data to M-Bus Slave (e.g. new baudrate).
STARTCHARACTER 68H
L-FIELD 03H
L-FIELD 03H
STARTCHARACTER 68H
C-FIELD 53H
A-FIELD XXH
CI-FIELD XXH
CHECKSUM XXH
STOPCHARACTER 16H
CON_ACK: Data format from M-Bus.
Master received and accepted.
SINGLECHARACTER E5H
M-Bus Slave to M-Bus Master:
RSP_UD1 Sends data to M-Bus Master
CON_ACK Acknowledgement of the receipt

The individual commands in detail

The Appendix describes all command formats.
Startcharacter: 10H = short format
C-field: 5BH/7BH = REQ_UD2
A-field: Address of M-Bus Slave modules
Checksum: Sum of A and C field, the two least significant
Hex digits
Stopcharacter: Always 16H
Startcharacter: 10H = short format
C-field: 40H = SND_NKE
A-field: Address of M-Bus Slave modules
Checksum: Sum of A and C field, the two least significant
Hex digits
Stopcharacter: Always 16H
Startcharacter: 68H = long format
L-field: Desribes the lenght of long format
Startcharacter: 68H = long format
C-field: 53H = SND_UD1
A-field: Address of M-Bus Slave modules
CI-field: Data field, B8H = 300 baud, BBH = 2400 baud
Checksum: Sum of A, C and CI field, the two least significant
Hex digits
Stopcharacter: Always 16H
of data from the M-Bus Master
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