Vacon CX Series - 7. Modbus-Vacon CX Interface; 7.1 Modbus Function Code Overview

VACON CX Modbus user’s manual Page 13
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7. MODBUS-VACON CX INTERFACE
Features of Modbus-Vacon CX interface:
• Direct control of Vacon CX ( e.g. Run, Stop, Direction, Speed reference, Fault reset)
• Full access to all Vacon CX parameters
• Monitor Vacon CX status (e.g. Output frequency, Output current, Fault code ..)
• Diagnostic of modbus communications
7.1 Modbus function codes
7.1.1 Function code 1, Read Control Bits
This function is used to read control bits.
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 bits CRC16
1 byte 1 byte 1 byte 1 byte 2 bytes
7.1.2 Function code 2, Read Status Bits
This function is used to read status bits.
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 bits CRC16
1 byte 1 byte 1 byte 1 byte 2 bytes
7.1.3 Function code 3, Read Parameters
This function is used to read VACON CX parameters.
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