Access Lev2 Pendant

I would like to build my own Lev2 Pendant. I have decent enough electrical / project skills. Does anyone know of the pinout for the RJ45 on this unit or have a wiring diagram? I would gladly buy one - I've only seen one for $850 and just seems like an unreasonable cost for maybe $50 worth of parts. If anyone has any insight it would be appreciated.

Thanks!