Overview

The defined modbus functions are implemented in the PLC library Tc2_ModbusSrv.

Modbus TCP function	Function code	PLC block
Read Coils	1	FB_MBReadCoils
Read Inputs	2	FB_MBReadInputs
Read Registers	3	FB_MBReadRegs
Read Input Registers	4	FB_MBReadInputRegs
Write Single Coil	5	FB_MBWriteSingleCoil
Write Single Register	6	FB_MBWriteSingleReg
Write Multiple Coils	15	FB_MBWriteCoils
Write Multiple Registers	16	FB_MBWriteRegs
Read/Write Multiple Registers	23	FB_MBReadWriteRegs
Diagnostic	8	FB_MBDiagnose

Requirements

Development environment	Target platform	PLC libraries to include
TwinCAT v3.1.0	IPC or CX (x86, x64, ARM^®)	Tc2_ModbusSrv