Master-Slave Communication via a CM PtP using the Modbus RTU Protocol
The application demonstrates how to:
configure the CM PtP RS422/485 HF as Modbus RTU master
configure the ET 200SP CM PtP as Modbus RTU slave
implement a Modbus RTU master and slave program in the program of a S7-1500 CPU
The example is designed such that the RTU master program as well as the RTU slave programs are realized together in one S7-1500 CPU. Here, the Modbus RTU master communication module is the S7-1500 CM PtP RS422/485 HF and the Modbus RTU slaves have been realized with the CM PtP communication modules of the ET 200SP. These Modbus RTU slaves in turn have been connected to the S7-1500 CPU via the ET 200SP head module. The two program parts (Modbus master and Modbus slaves) can be easily separated by you and can be adjusted to your own applications.
The figure below shows the hardware setup of the example.
Current version 2.1 for STEP 7 Professional V15.1 (TIA Portal)
Documentation (1,3 MB)
Project for STEP 7 Professional V15.1 (TIA Portal) (2,1 MB)
Communication via the CM PtPs of the ET200 SP and the S7-1500 using the Freeport Protocol
Master-Slave Communication with Modbus RTU Protocol for S7-300 and ET 200S Systems
How do you establish a MODBUS-RTU communication with STEP 7 (TIA Portal) for the SIMATIC S7-1200?
Correction of receive line initial state ("Modbus_Comm_Load".LINE_PRE)