[mkoval]

We solved this problem on our robot today. One of the connectors on the ribbon cable between the cRIO module and digital sidecar was not crimped tightly enough. This may be your problem as well if you received a faulty ribbon cable and had to correct re-crimp the connector yourself. Even if it superficially looks correct, it may not be crimped tightly enough to make the connections.

Check the LED next to the RSL connector on the digital sidecar. If it is not illuminated, then this is likely your problem.