Supported Modbus RTU function codes
Supported methods for reading or writing Modbus RTU data items.
Operation | Size | Data source | Function name | Function code |
|---|---|---|---|---|
Read | 1 bit each | Application program | Read Coils | FC 1 |
1 bit each | External | Read Discrete Inputs | FC 2 | |
16 bit each | Application program | Read Holding Registers | FC 3 | |
16 bit each | External | Read Input Registers | FC 4 | |
Write | 1 bit | Application program | Write Single Coil | FC 5 |
16 bit | Application program | Write Single Register | FC 6 | |
Write | 1 bit each | Application program | Write Multiple Coils | FC 15 |
Write | 16 bit each | Application program | Write Multiple Registers | FC 16 |