Red Lion DSP to Mitsubishi F700 via MODBUS

[Frippy]

Greetings all,
I am seeking some help and direction on controlling a Mitsubishi F700 VFD from my Red Lion DSP. I have been able to read data from the VFD but when I try to write commands to it there is no change in the drive.

I am using the MODBUS master protocol on the Red Lions RS-485 port and the RS-485 terminals on the Mitsubishi.


Thanks in advance for your help.

 

[JeremyH]

Hello,
What modbus registers are you writing to? Are you sure the registers are read/write in the VFD?

Thanks
Jeremy

 

[Frippy]

Jeremy,
Thanks for the reply. I found the issue to be the built-in line resistor on the F700. I switched it to off and the communication was perfect.