In FS the audio panel is "fux0red" so that either COM1 or COM2 is always "listening" - or both (but that means you need to press the "BOTH" mode button.
Looks like COM1 vs COM2 audio works as a toggle - either COM1 or COM2 - no matter what you try, one of them is active in any case.
Then again, the audio panel does not even simulate transmit mode, just listening. On real audio panels you can have everything off, or you can even listen to COM1 while accidentally transmitting to COM2 and wondering why the ATC is not responding..
Not that it is a good feature though.
I suggest you use led buttons and just build it like the FS2004 audio panel, and wire the leds to the fsuipc offsets, so it works like the one in FS. Not strictly realistic, but the audio panel is not very much used anyway unless you fly in VATSIM or such, and only when Squawkbox v3 is released there is not much support for audio panel stuff.
Our audio panel, using toggle switches:
Simulator in action, looking hard at the Jeppesen landing chart and trying to find the airfield..
More pics, some of the sim, some of our aviation club, some of just planes around there:
http://tigert.gimp.org/gallery/MIK
Oh, and since someone will ask anyway:
* FSBUS for radios and switches (
www.fsbus.de)
* Simkits for instruments (
www.simkits.com)
* A Cessna 150 fuselage for the cockpit
* Collimated display donated by Finnair, originally from a retired DC-10 sim
* 1.5 years, probably over 2000 man-hours
* Yes, we are very happy about it, and it was worth the sweat!
Huge greetings to Dirk and everyone who is sharing their inspiration and inventions, without you this wouldnt be possible!
Best,
//Tuomas