Hello guys,
I have a Omron VFD (3G3MX2). I am trying to learn Modbus communication and can you please give me the wiring diagram from drive DB9 connector. I have used Modbus poll before with Altivar drives.
I tried connecting RS- to DB9 pin2 and RS+ to DB9 pin 3 but it doesn't work. I have configured the drive parameters Modbus frequency command and Modbus run command,
Thanks

 

The Modbus (RS-485) connection for that drive is the "SP" and "SN" terminals located on the terminal block. You need to wire the drive's "SP", "SN", and "L" terminals to a USB to RS-485 adapter's +, -, and GND (a.k.a. COM or REF) terminals, respectively.

I also recommend ensuring that the termination dip switch on the drive is set such that termination is disabled (disconnected).

I'm not sure where the DB-9 connector and the RS+ and RS- signals you mention come from. Pins 2 and 3 on a DB-9 are typically for RS-232, which is not electrically compatible with RS-485.

 

Thank you very much,.