Vacon CX Series - Function Code 4, Read Variables; Function Code 5, Write Control Bits; Function Code 6, Write Parameter; Function Code 8, Diagnostic

VACON CX Modbus user’s manual Page 14
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7.1.4 Function code 4, Read Variables
This function is used to read VACON CX variables.
The transaction frames:
Query:
Slave
address
Function
code
Starting
Address HI
Starting
Address LO
Number of
points HI
Number of
points LO
CRC16
1 byte 1 byte 1 byte 1 byte 1 byte 1 byte 2 bytes
Response:
Slave
address
Function
code
Byte count Data HI Data LO CRC16
1 byte 1 byte 1 byte 1 byte 1 byte 2 bytes
7.1.5 Function code 5, Write Control Bits
This function is used to set or clear control bits.
The transaction frames:
Query:
Slave
address
Function
code
Output
Address HI
Output
Address LO
Force Data
HI
Force Data
LO
CRC16
1 byte 1 byte 1 byte 1 byte 1 byte 1 byte 2 bytes
Response:
Slave
address
Function
code
Output
Address HI
Output
Address LO
Force Data
HI
Force Data
LO
CRC16
1 byte 1 byte 1 byte 1 byte 1 byte 1 byte 2 bytes
7.1.6 Function code 6, Write Parameter
This function is used to write VACON CX parameters.
The transaction frames:
Query:
Slave
address
Function
code
Register
Address HI
Register
Address LO
Data HI Data LO CRC16
1 byte 1 byte 1 byte 1 byte 1 byte 1 byte 2 bytes
Response:
Slave
address
Function
code
Register
Address HI
Register
Address LO
Data HI Data LO CRC16
1 byte 1 byte 1 byte 1 byte 1 byte 1 byte 2 bytes
7.1.7 Function code 8, Diagnostic
Diagnostic function uses the subfunction code field in the query to define the type of test to be performed.
The transaction frames:
Query:
Slave
address
Function
code
Subfunction
HI
Subfunction
LO
Data HI Data LO CRC16
1 byte 1 byte 1 byte 1 byte 1 byte 1 byte 2 bytes
Response: