Modbus RTU over RS485 slave library for Nano

[pylon]

As you don't specify any requirements I assume you can live with any implementation. I used this library
for one of my projects.

@MaverickRF

(I previously attempted to use Modbus TCP but unfortunately, the Arduino Nano doesn't work with the Wiznet W5100-based Arduino Ethernet Shield for Uno/Mega)

A shield for the UNO should work on the Nano as both use the same processor and run on the same voltage.