Circutor CVM-A1000, Instruction Manual

Page: 338 / 378

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-A .
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 device:
• Serial number: the last 8 digits of the CVM-A serial number.
• Manufacturer ID: CIR
• Device type ID: Electricity�
• Version ID: hardware/firmware version of the device.
B�- Data blocks with variables:
Each block contains one
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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-A1000 - CVM-A1500
Instruction Manual