General steps to establish master-slave communication between two S7-1200 PLCs

Master & Salve With PLC S7-1200

 

The term "master-slave" is often used in the context of communication between multiple devices, where one device (master) controls and communicates with one or more other devices (slaves). For PLCs (Programmable Logic Controllers) such as the Siemens S7-1200, the master-slave concept can be used to establish communication between multiple PLCs.

 

The following are the general steps to establish master-slave communication between two S7-1200 PLCs:

1. Configure network settings: Make sure both PLCs are connected to the same network and have unique lP addresses. Set network parameters, such as subnet mask and gateway.

2. Set up the communication protocol: Configure the necessary settings on both PLCs according to the selected protocol (e.g. Modbus TCP/lP or Profibus). This typically involves defining communication parameters such as the lP address and communication port of the slave PLC.

3. Programming the Master PLC: Write a program for the Master PLC in programming software (e.g., Siemens TlA Portal) that includes instructions to establish communication with the slave PLC, send commands, and receive responses.

4. Programming the Slave PLC: Similarly, the Slave PLC is programmed to listen for commands from the Master PLC and perform the desired actions. This can involve setting up input/output modules, defining variables, and implementing the necessary logic.

5. Test and debug: After writing and downloading the program to the appropriate PLC, test the communication by running the program and observing the expected behavior, monitor the communication status, check for any error messages, and troubleshoot if necessary.