[mikegrundvig]

You mention onboard computer so I assume you are putting a separate computer on the robot. Have you thought about using a null-modem cable and a serial connection? The cRIO appears to have raw serial support and the serial port is generally quite simple to use - lots less machinery than even a restful server and HTTP. Most good serial apis (and I know there is at least a few good Java ones) let you send and receive a variety of data types. Worst case scenario would be to use strings. I know the cRIO can send bytes as well as use things like printf with the serial port.

-Mike