Does the board pass the diagnostic util? I presume you are talking about the C examples in C:\Program Files\National Instruments\NI-CAN\Examples. What is the NI-CAN driver version that you have? I hope you have the latest CAN driver available from ni.com > Support > Product Reference > Drivers and Updates > Current Versions. If you have a 2 port board run the obj2obj.exe example with the cable looped with termination resistors. Hope this helps.