Function Codes Supported by Modbus RTU Slave
The Modbus RTU Slave Communications option supports the Modbus function codes listed in the following table. As well, the maximum number of coils or registers that may be specified or included in a single Modbus message is also given.
Function Code | Description | Maximum # of coils / registers |
1 | Read Coil Status | 2000 |
2 | Read Input Status | 2000 |
3 | Read Holding Registers | 125 |
4 | Read Input Registers | 125 |
5 | Force Single Coil | 1 |
6 | Force Single Register | 1 |
15 (0x0F) | Force Multiple Coils | 800 |
16 (0x10) | Preset Multiple Registers | 100 |