ModbusTCP functions
In the Modbus protocol, the functions determine whether data is to be read or written, and what kind of data is involved.
Function | Code | Description |
|---|---|---|
1 | Read digital outputs | |
2 | Read digital inputs | |
3 | Read analog outputs and inputs / GPR | |
4 | Reading the inputs / GPR | |
5 | Writing a digital output | |
6 | Writing an output / GPR | |
8 | Diagnostics | |
15 | Write a number of digital outputs | |
16 | Writing several outputs / GPRs | |
23 | Write and read a number of process data outputs / GPRs |
GPR (General Preset Register) - register structure of the Modbus interface (see appendix)