BMENOC03x1 communication module

[28/11/2024]

Modicon communication modules:

  • BMENOC0301
  • BMENOC0321

can act independently from CPU. The most important thing is to be aware of that. Either You will turn that information into advantage or it will cause You troubles.

Anyway, using those modules simplifies configuration a lot. It is enough to install them in the chassis and indicate IP address in the configuration. They will automatically respond to Modbus TCP requests. They will respond with data held in CPU memory (like %M, %MW, %I). And here is a catch. They will respond even if Your controller is in STOP mode. In a result, Modbus Client will never know whatever data are “fresh” or not. In this case, I recommend selecting one register with free running counter assigned. PLC code may look like this:

You may also implement so called “live bit” toggling every certain amount of time but I am not a fan of this solution because on the Modbus Client side, You need to think how fast the bit should be scanned.


      print("SYSTEM.PAUSED");