Hello Michael,
Jim has a small Hamlib server built into Quisk and I guess that as the autotuner function has not been implemented in Hamlib (yet) he has added an unused command (U) to accomodate several requests he has had from users. As I will be generating the call directly from my remote control software the use of a not officially implemented command is not a problem for me. Your messaqge has cleared up the why rigctl didn't work for me but Telnet did.
One day we will have to face the issue of the "U" command being implemented and not necessarily for a tuner but if you are showing some interest in getting this function into Hamlib that will be a good thing. My autotuner is a home brew one and I initiate a tune by pressing a button on its front panel or sending a tune signal from my remote controller (which simply blips a relay in parallel with the button) and the tuner waits for RF to appear and starts tuning when it does. At the completion of tuning it stops and sends an "I'm finished" signal back to the Remote Controller. I think that a lot of commercial tuners work like this and the becoming popular open source AT-100 series tuners by David Fainitski certainly work this way. Other tuners check the SWR continuously and if deviating too far automatically tune with no user intervention.
My issue was that when I pressed the tune button I needed Quisk to press its spot button so I had two different pieces of software that needed to talk to each other and I wanted to keep to a standard interchange - enter Hamlib.
73, Graeme ZL2APV
