Hmmmmm... Guess I didn't do a very good job with the terminology, so I'll give it another try. I said UDP not based on personal knowledge, but based on the fact that to get the communications to work between WSJT-X and Commander I went to the reporting tab of WSJT-X settings and entered the UDPServer IP address (127.0.0.1) and the UDP server port number (2237) and checked off three boxes that had to do with UDP requests. Then, in a panel called Secondary UDP Server, I checked a box saying "Enable logged contact ADIF broadcast" and again plugged in an IP address and server port number. The box up the page aways that said "Use TCP/IP" address was NOT checked.
The N4PY Icom software is basically the same as the Pegasus software for all the other brands. N4PY told me that the technique I referred to was special for communications with DXLab, but maybe that's not true either? Anyway, in Commander config, General Tab, Radio panel, I selected Pegasus_N4PY as the model and then specified the location of a "control folder". In the N4PY program settings, I specified the name of that same folder, which they call the "Transfer folder". And, N4PY and Commander were able to successfully communicate via that folder.
And, what I tried to tell you is this: When I use that means of communications between N4PY and Commander, Commander no longer responds to the request from WSJT-X to turn on PTT when I run the PTT test in WSJT-X.
Getting back to Commander and my WSJT-X problem: If I specify the radio as an IC-7610 (with direct connection to the 7610 USB CAT port), then a box appears in the radio panel below the model area that says "Verify CI-V command acceptance". If I fail to check that box, then the WSJT-X PTT test fails in exactly the same manner as when I'm using the control folder with the port controlled by N4PY. I check that box, and then the WSJT-X PTT fest completes properly. So, that's the story. If it still doesn't make sense, I'll just have to find another way to makes things work. Thanks for your time.