This question is an exact duplicate of:

In my current project I have to communicate with 10 different devices with PLC.

PLC is the master. When input comes from PLC to a device, the Arduino controller through RS485, I want to check the input and perform an action accordingly and once completed need to send acknowledgement back to PLC.

Communication protocol is MODBUS can some one suggest something on it.

I am completely new to Arduino and PLC.

If there is any sample program which I can check, it will be more helpful


marked as duplicate by Majenko arduino-uno Mar 18 at 12:13

This question was marked as an exact duplicate of an existing question.

  • you forgot to ask a question – jsotola Mar 18 at 18:12
  • Please give me some references where i can understand the concept and i do – Saiteja chinthalapati Mar 19 at 8:55