Thanks for the reply, Alex.

I've re-read my question this morning and I've not actually explained what I'm trying to say very well!

The problem is when I move the knob on the transponder from standby into mode C etc in the sim, it doesn't change the setting on the pilot client. When it is is mode C TA/RA I can see online traffic on the map and get TA/RA if in a conflict situation, so there is definitely some interaction going on.

In terms of functionality with regards to being able to dial in the squawk code and ATC seeing it, there is no problem.

Hope that makes it a little clearer.