Here is the trigger cable that is used;
http://www.flytron.com/rc-camera-shutters/307-sony-multi-terminal-rc-shutter-for-a7-a7r-nex-3nl-a5000-a6000-a58-a3000-hx300-rx100ii.html
Here is the hot shoe that is used;
Here is the hot shoe cable that is used;
Only the signal wire (white) from the flytron cable is used and plugged into port 7 or 8 on the pixhawk and the red and black are attached to a UBEC set to 5.0V. The flytron cable sends the signal from pixhawk to camera to activate. The hot shoe picks up the shutter activation and feeds that activation back to Reach.
This link shows a pic of the wiring attached from the A6K to Reach.
Makes sense?
Cheers,
Tim