if you want to change the transponder mode of IVAP directly with the Radio Unit in the cockpit, here you have the LUA code to use :
function sqmode(varname, value)
if value==0 then
--squawk mode TX
ipc.writeSB(0x7B91, 0)
else
--squawk mode stand by
ipc.writeSB(0x7B91, 1)
end
end
function sqident(varname, value)
if value==1 then
--squawk ident
ipc.writeSB(0x7B93, 1)
end
end
event.Lvar("ON_STBY_Select", 500, "sqmode")
event.Lvar("BTN_G90GTX_RTU_IDENT_KEY_PRESSED", 500,"sqident")
Don't forget to put the name of your LUA file in your FSUIPC.ini
For example, with my LUA file nammed "transponder_carenado" :
[LuaFiles]
1=transponder_carenado
[Auto]
1=LUA transponder_carenado
Have fun and fly safe