[elstaqub]

I know it's been said already, but to confirm - you need a null modem cable or adapter. Your wires are crossed - there are wires in the cable for sending and receiving in either direction, and the PC and CRIO disagree about who should use which.

The kernel code in the CRIO puts out a lot of messages before your code even starts, so you'll know whether it's working regardless of what's in your code.