The FlySky FS-I6 RC transmitter has provision to connect two transmitters together via a special trainer/student cable. A female S-Video connector presents 1=PPM OUT, 2=PPM IN, 3=TX, 4=RX, Case=GND signals to the trainer/student cable. What is the correct pinout of the trainer/student cable? I came here to find the answer rather than googling for an opinion. Thank you for your help.