Good news anyway ! It happened to me in the early 90's when i was playing with transceivers/packet radio tncs/pcs and other RS232 "toys" so i wanted to try again and ...: it works! What? I simply connected GND and TX of the USB RS232 converter to the port B of the AVMAP docking station which is supposed to be TTL and magically works. So for now i am set, if i could just configure the same port for a GPS input that would be perfect.
System tested in some hours of flight friday and saturday last week, it works perfectly.
Federico