As IoT Edge ModBus Module RTU mode cannot run on Windows, and so many RTU devices are connect to Windows Platform, so here is a simple script of how to obtain data from RTU device and send to Azure IoT Hub.
Packages for communicating with RTU Device is pyserial.
Test using simulated device on Windows platform.
Put you IoT Hub Connection String to the script and run.
As there are different kinds of data format, please test and configure on real data before use !