Protech Systems SI-W309 User Manual page 37

Offset Description
00 Slave ID address
01 Function Code
02 Byte Count
03 ~ Output channel
03+(N-1) Readback value
03+N ~
03+N+2
Error Response
Offset Description
00 Slave ID address
01 Function Code
02
03 ~ 04
SI-W309 SERIES USER MANUAL
Counts
1 Byte
1 Byte
1 Byte
N Bytes
2 Bytes
CRC
Counts
1 Byte
1 Byte
Data 1 Byte
CRC 2 Bytes
Chapter 4 MODBUS RTU Protocol
Data
1 to 255
0x01
1 or 2
Corresponding to Byte
count
Produced by firmware.
Data
1 to 255
0x81
0xCD: No function
Produced by firmware.
Page: 4-6