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CVM-BDM supply network analyzer
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12.3.- MODBUS © protocol
The CVM-BDM analyzer can communicate by means of the
MODBUS
©
protocol, as it is following described:
When the CVM-BDM communicates with MODBUS protocol, it uses the
RTU
mode
(Remote Terminal Unit ). Each 8-bits byte in a message contains two 4-bits
hexadecimal characters.
The format for each byte in RTU mode is :
*
Code
:
8-bits binary,
hexadecimal 0-9, A-F
Two hexadecimal characters
contained in each 8-bits field of the
message.
*
Bits per Byte
:
8 data bits
*
Error Check Field
:
Cyclical Redundancy Check (
CRC ) .
MODBUS FUNCTIONS:
FUNCTION 01
Reading of relay state
FUNCTION 3 or 4
Reading of n Words (16 bits-2 bytes). This function
permits to read all the electrical parameters
of the
CVM-BDM. Each parameters is a 32-bits long,
hence two words are required to inquiry for a
parameter.
FUNCTION 05
Writing one relay
