MultiModbus is an Arduino library that supports multiple Modbus RTU servers and clients over RS485 on one board. RS485-to-UART ICs are required.
MultiModbus supports multiple Modbus servers/clients on one board. Modbus messages are exchanged over RS-485 wires, requiring a MAX485 IC for each channel to convert the RS485 signal to a UART.
The official ArduinoModbus is a powerful and intuitive library based on ArduinoRS485 and libmodbus. However, it is designed for MKR boards only and fixed to use hardware Serial1. MultiModbus leverages ArduinoModbus RTU class and Robert Tillaart's RS485 to enable using different hardware/software serial ports. In this way, our library can run multiple Modbus servers/clients on one board.
We have successfully run our library on MEGA, UNO, and NANO using SoftwareSerial. However, keep in mind that SoftwareSerial library may conflict with other comminucation libraries such as Wire, so our library is best run on a board with multiple hardware serial ports.
We provide a Modbus server example. You can use the EasyModbus to read/write the coil of the server. The code has been tested on various boards including Arduino NANO, MEGA, and UNO. The maximum number of servers/clients depends on the target boards.
