com0com creates ports in pairs. I always seem to want to put in the first port in the pair, in this case Com 16 instead of the second port COM 17. Once I spotted that in Win4Icom and corrected it I was in business. Thanks for responding.

Well, as Gary said, "Fairly simple". I had the incorrect COM port set in WIN4Icom. Once corrected working fine. 👍

When I tried it I got a message back that the port designated in the Win4Icom 3rd party set up was not being released and so VarAC could not send information to the radio. No doubt I have some setting wrong but I experimented with several things and had no luck. Maybe a port setting in VaraAC or in the VARA modem? I am in over my head on this. A screenshot of a working configuration would be a big help. THANKS

While waiting for a response I began to play with some of the CAT setting. One of the things I tried was to change the DTR and RTS settings from H to L. My problem seems to have resolved. Don't really know what I am doing but not going to argue with success. Looking at my WSJTX settings neither DTR or RTS settings seem to be a factor when CAT is selected. Maybe someone who understand all of this can educate me? Always interested in learning.