Hello Mr Dowson,
Thank you very much for this quick response, I really appreciate it!!
Well, I did some tests after your reply and here is the situation:
The commands AP_N1_HOLD, AP_N1_REF_DEC, AP_N1_REF_INC, AP_N1_REF_SET - they all work fine and do exactly what they should do - I checked them trough offset 3110 with fsbus.
With the other offsets I just went crazy because whatever I did, I couldn't extract anything different then zeros, using both ways - with fsbus and FSInterrogate2std.exe and cycling trough all possible situations and airpanes in FSX.
So these are the offsets that I was trying to read:
07FA, 07F4 (as you referred and as they are in the documentation) and offset 07F8 which I found marked in FSInterrogate as "AP RPM Value (?)". Anyway - from all 3 offsets I read only zeros all the time with no matter what I change in FSX. May I kindly ask you to check what's wrong with them - when you have time of course, its not an emergency :).
Anyway - I can continue using offset 3110 to manipulate them, but it will be great if there is a way also to read the n1_hold button status and n1_ref value.
Thanks again and best regards
Boris Staykov