Modbus communication with a breakout box

[M3GAPL3X]

Hi Guys,

I have a VFD that I want to control via Labview. From the spec sheets of the VFD, it says that I can use " 

RS-485 and RS-422 serial communication as a standard". My question is, that I will be only reading or writing to the VFD via Labview and I want the control to be integrated into my main program (I have various other sensors I need to control with just one VI), I can use analog output from my breakout box (an SCC-68) with one wire and recieve and one wire as transmit for serial communication? I am confused on how I should go about doing this as I never dealt with this before.

Thanks in advance!

[RavensFan]

Do you want to control the VFD using serial or analog?  Modbus serial communication has nothing to do with analog outputs or the SCC-68 breakout box.  You will need either an RS-485/RS-422 serial port on your PC, or a USB to RS-485, or an RS-232 to RS-485 adapter.  RS-485/422 serial communication is either 2 wire or 4 wire.  There is either 2 wires which are a differential pair that handles both transmitting and receiving.  Or 4-wire, 2 pairs where one pair handles transmitting and the other receiving.