ABB A43 - Page 184

Communication with M-Bus
A43/A44 184 2CMC48001M0201
User Manual Revision: C
A-Field
CI-Field
The A-Field (address field) is used to address the recipient in the calling
direction, and to identify the sender of information in the receiving direction.
The size of this field is one byte, and can therefore take values from 0 to 255.
The following table shows the allocation of addresses:
Address
Description
0
Factory default
1-250
Can be given to meters as individual primary addresses, either via the
bus (secondary addressing) or via the buttons directly on the meter.
251-252
Reserved for future use.
253
Used by the secondary addressing procedure (FDh).
254
Used for point-to-point communication (FEh). The meter replies with its
primary address.
255
Used for broadcast transmissions to all meters (FFh). None of the meters
replies to a broadcast message.
The CI-field (control information) codes the type and sequence of application
data to be transmitted in the frame. Bit two (counting begins with bit 0, value 4),
called M-bit or Mode bit, in the CI-field gives information about the used byte
sequence in multi- byte data structures. For communication with the meter, the
Mode bit shall not be set (Mode 1) meaning the least significant byte of a multi-
byte record is transmitted first.
The following table shows the codes to be used by the master:
CI_Field codes
Application
51h
Data send
52h
Selection of slaves
B8h
Set baud rate to 300
B9h
Set baud rate to 600
Bah
Set baud rate to 1200
BBh
Set baud rate to 2400
BCh
Set baud rate to 4800
BDh
Set baud rate to 9600
BEh
Set baud rate to 19200
BFh
Set baud rate to 38400
The meter uses code 72 in the CI-Field to respond to requests for user data.