I have a couple of FlySky FS-i6X RC transmitters that I'd like to use to teach my brother how to fly. I've seen other people use "buddy box" cables that connect two transmitters and allow one person to temporarily give the other control of the aircraft while in flight.

The back of the transmitter has a port that looks like an old S-video receptacle. Can I use that to make a buddy box cable?

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Yes, on both counts! That is an S-video (aka. Mini-DIN-4) connector, and you can use it to make a buddy box cable. The port carries a 4-channel CPPM signal that can be used by cheap USB adapters as a joystick HID input to your computer or for buddy box mode, which FlySky calls "Trainer mode". I've made one for my own use, following the specifications laid out by the user gcartled on the RCGroups forum.

Making the Cable

It appears that there are sellers with listings for ready-made FlySky trainer cables, like this one on eBay, but I haven't tested them to confirm that they work.

After obtaining a spare S-video cable (or creating your own from Mini-DIN-4 male terminations), chop it somewhere in the middle and reorder the connections for the 4 internal wires such that the pins 1 and 2 are connected to the opposite number on the other end of the cable. i.e.:

  • pin 1 → pin 2
  • pin 2 → pin 1
  • pin 3 → pin 3
  • pin 4 → pin 4
  • metal housing → metal housing

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This creates a crossover cable that allows the CPPM signals from the "slave"/trainee transmitter to be received by the "master"/trainer transmitter.

Configuring the Trainer Transmitter to Enable "Trainer Mode"

In order to use trainer/trainee functionality, the appropriate settings must be configured on the trainer's transmitter so that it knows what switch will be used to toggle on/off control inputs from the trainee's transmitter. In this setup, the trainer's radio is the only one bound to the aircraft.

These instructions are confirmed functional for the FS-i6X transmitter, but it is likely to also work with the FS-i6 and other derivatives:

  1. Turn on the transmitter.
  2. Hold the OK key to open up the menu.
  3. Scroll to System Setup and select with the OK key.
  4. Scroll down to Trainer mode and select with the OK key.
  5. Scroll using the OK key so that the horizontal arrow points to Mode and then use the UP key to change from Off to On.
    • If you want to disable buddy box functionality in the future, come back here and change the Mode back to Off.
  6. Scroll using the OK key so that the horizontal arrow points to Switch and then use the UP and DOWN keys to select the switch that you'd like to use to enable/disable buddy box functionality.
    • (WARNING: you shouldn't have this switch bound to anything on your aircraft, as this could cause issues inflight when something is accidentally triggered in the process of enabling/disabling the biddy box)
    • Note the position of the switch you selected that changes the text Inactive to Active at the bottom of the screen. The Active position enables the buddy box and vice versa.
  7. Hold the CANCEL key until you hear a beep to save the changes and then press CANCEL twice more to escape the menus all together.

Now, go and fly!

  • $\begingroup$ Are pins 3 and 4 required? Is the above programming for the master or student transmitter? $\endgroup$ – Robin Bennett May 27 '20 at 8:21
  • $\begingroup$ Also, it appears that you can just buy an offical Flysky buddy box cable for $10-15, from multiple sellers. $\endgroup$ – Robin Bennett May 27 '20 at 8:25
  • $\begingroup$ @RobinBennett I have not verified that to be the case. It appears you are correct about the ready-made cables, but I haven't tested them to confirm that they work. $\endgroup$ – ifconfig May 27 '20 at 15:15
  • $\begingroup$ Also, my answer clarifies which transmitter's settings need to be changed, the trainer's/master transmitter $\endgroup$ – ifconfig May 27 '20 at 22:16
  • $\begingroup$ Thanks, I'd missed that. Do you have to do anything to the student's transmitter? $\endgroup$ – Robin Bennett May 28 '20 at 9:26

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