An example of communication between arduino MEGA and variable frequency drive over Modbus.
I've used this code as basis for one of the projects I've been involved. We've automated the 7.5kW blower for wheat drying process. For the Modbus part we've used a MAX485 module and created a circuit using a protoboard.
We've used a Machtric VFD and decided to control it over the Modubus, since it opens a wide range of possibilities (not just standard run/stop/frequency commands).
Photo of the (almost) finished project:
NOTE: This code is just a Modbus example and not a wheat drying blower project code.