When asking for technical help at the very least let us know the version of firmware you are running.Cliff's Calibration (Mapping) Guide is a MUST READ: http://www.vemssupport.com/forum/index.php/topic,97.0.html
There's your answer. 5 analog inputs, second wheelspeed input, second rs232 (for AiM Display or GPS input) and a 5V and GND for convenience.
Got it working! https://youtu.be/cTEBCJr-ELw