I've been working with this board for a few weeks, but with what I understand from the documentation I have read, you would have to implement any protocol yourself. For your application, you can probably come up with a simple protocol to use. I do know that you should only drive the digital pins with one device at a time. I think in the documentation it says you can destroy the board if you are driving a pin high and the receiver is doing the same.
If there is a preimplemented protocol with the board, the NI guys will probably respond.