CIRCUTOR CVM-B Series - Manual (Page 294)

7�8�5�- M-BUS COMMUNICATIONS
The M-Bus module implements a slave M-Bus interface that is compatible with the EN13757-2
and EN13757-3 standards, enabling the direct reading of up to 38 electrical parameters of the
CVM-B.
Network access is accomplished with a M-Bus transceiver that is self-powered from the same
bus and galvanically isolated from the rest of the circuit.
The data-reading protocol on the M-Bus network is as follows:
1�- The M-Bus network master requests data reading from the slave by sending the “REQ_UD2”
telegram (user data request).
2�- The slave responds with the “RSP_UD” telegram (user data response).
The “RSP_UD” telegram has 2 different parts:
A�- A header with a static structure, containing relevant information about the unit:
• Serial number: the last 8 digits of the CVM-B serial number.
• Manufacturer ID: CIR
• Device type ID: Electricity.
• Version ID: hardware/firmware version of the unit.
B�- Data blocks with variables:
Each block contains one CVM-B variable. To describe the data, the M-Bus protocol specifies
that there must be at least:
• one DIf field that defines the format of the data being sent.
• one VIf field that defines the units in which the data are expressed.
Depending on the data type, format extensions ( DIfe) and/or unit definition extensions (VIfe)
may be required.
The maximum length of the “RSP_UD” telegram is 255 bytes.
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CVM-B100 - CVM-B150
Instruction Manual