[Radical Pi]

The data sheet says to use 120 ohm resistors, but in the cable assembly guide it says that 100 ohm work just fine.

Also, since you are using serial mode, there should be 2 resistors. One of them is in a jack at the end of the chain, and the other is inside the serial adapter, bridging the green and red wires.

I guess the only thing left to check is your wiring. Are you using a 6-conductor wire between the cRIO and the black jag? Have you tried a different wire? Are you sure you made the apapter properly? The end result inside of it should have been the red and green wires connected to a resistor, 3 more going to the DB-9 connector, and one left free. I remember I didn't have the bus working for a while because I didn't push the pins all the way into the DB-9 port