http://www.magiclantern.fm/forum/index.php?topic=12022.0 (http://www.magiclantern.fm/forum/index.php?topic=12022.0)
Atomos recorders to be triggered to record by a HDMI trigger from the camera called REC COMMAND.
This works fine with the camera set to record h264 video but unfortunately it does not work yet when you're recording RAW.
And it seems related to timecode not being send when recording raw in the camera