Communication between PLC and Arduino Based on Modbus Protocol

This paper explains how to set up the communication between PLC and Arduino based on Modbus Protocol. PLC is a master and Arduino is a slave. A Fx2N-48MR, a Fx2N-485BD, an Arduino main board and an I/O Expansion V5.0 are used to finish a test. How to organize the data package in the Modbus RTU is explained. Both the programming of PLC and Arduino are interpreted. The test result and conclusions are given at last.