Zenmuse Z15 / Sony NEX / Hotshoe sync signal

[DMIOM]

Currently upgrading photogrammetry rig, previously using "Photohigher" gimbal with constrained movement so it was OK to run a cable from hotshoe to trigger eventlog (& hence get accurate position after post-processing).  With Z15 and its sliprings, has anyone found a way to get a sync signal back from the camera? (I know we can – and did – log the shutter release request but want to capture the actual release event).

Dave (IOM)