I'm looking for a solution to remotely control an electrical motor via ModBus RTU. For this arrangement, there is a Raspberry Pi that runs NodeRed, connected via LAN with a Controllino MEGA (Arduino Mega 2560), a Schneider ATV930 connected to the Controllino MEGA via RS485 and, of course, the electrical motor.
Up to now, at my understanding level of Arduino programming, I've been able to connect some sensors, display their info in NodeRed and send some commands to Controllino via MQTT, but I can not fully understand how to make the MQTT transition to ModBus RTU to control the electrical motor.
Googling for similar projects, I have found this project where the author managed to control an electrical motor with Arduino MEGA and a Schneider VSD via ModBus. Also there is a ModBus RTU example for Controllino at this adress.
Thanks in advance for opinions, suggestions and solutions