MODBUS

Hi I'm trying to get my arduino to communicate with my VFD via modbus 485 protocol but dont know how to do this. i need help from simple wiring to a sample program sketch.

This is what i need to send to set up frequency:
7) Example 1: Write 30.00Hz to inverter of 0l
Sent data: O1H 02H 03H 00H 0BH B8H 7FH 0CH

but i dont know how to write it into the modbus line.
i checked out this: https://sites.google.com/site/jpmzometa/arduino-mbrt/examples but those examples are too complicated i need something simple.

i'm using this as converter from rs-232:
http://www.ebay.com/itm/150921115323?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Thanks for any help

Hi,

Have you tried SimpleModbusMaster? Its easy enough to setup.

https://code.google.com/p/simple-modbus/

If your using RS232 to communicate between the VFD and arduino you will need a TTL232-RS232 level shifter ic like the MAX232 on the arduino side. If its RS485 you will need a driver ic like the MAX485/487.