In order to vet out the Modbus communication, I've been trying to read the value of Node 0. My command is set up as a function #4 of registers 30200-30201, however, I am still getting exception code

To confirm I am able to read values over Modbus, I set up a command to read input register 30200 - this is command function #4. I've always been getting back exception code 2 though.

"Go to the control panel and Sound applet. On the voice tab I had to set the default playback device to Modem #4 Line Playback"

I found the problem. I had to go to the control panel and Sound applet. On the Voice tab I had to set the default playback device to Modem #4 Line Playback. This may be a different device on other sys