The rear USB port goes to the video board and the front USB port goes to the Control board. You can use rcon commands to to get to the video board (slot 9) from the control board USB port but I am trying right now with one in my office and I do not seem to be able to get to the control board from the video board USB port. I'm sure TruBlue support could walk you through what you can do from the video board.?
