SUTO S421, Instruction And Operation Manual, Page: 39 / 44

15 Appendix A Modbus communication example
15 Appendix A Modbus communication example
03 (0x03) Read holding register
Request Response
Slave address 1 byte Slave address 1 byte
Function code 1 byte Function code 1 byte
Starting address
Hi 1 byte Byte count 1 byte
Starting address
Lo 1 byte Register Hi 1 byte
No. of points Hi 1 byte Register Lo 1 byte
No. of points Lo 1 byte : :
CRC 2 bytes Register Hi 1 byte
Register Lo 1 byte
CRC 2 bytes
05 (0x05) Write single coil
Request Response
Slave address 1 byte Slave address 1 byte
Function code 1 byte Function code 1 byte
Coil address Hi 1 byte Coil address Hi 1 byte
Coil address Lo 1 byte Coil address Lo 1 byte
Data Hi 1 byte Data Hi 1 byte
Data Lo 1 byte Data L 1 byte
CRC 2 bytes CRC 2 bytes
S421 39