I am attempting to help one of our summer interns get the PXI-8512/2 (2 port) CAN working. I am not familiar with this device and have a couple of questions since I did not find one of the questions in the on-line documentation or I was not looking in the right place.
1) There are 4 LEDs at the top of this board. What does each LED represent? I could not find this in the documentation or missed it.
2) The intern is attempting to build a short cable to loop port 1 to port 2 to learn how to use the CAN bus, CAN DB9 connectors. He has wired
pin 2 to pin 2 - CAN_L bus line
pin 7 to pin 7 - CAN_H bus line
pin 5 to pin 5 - Shield (optional)
At one point he had the 120 ohm resistors for cable termination in place but then removed them as he thought that was done on the board or so his lead told him. He said he also tried using 60 ohm resistors.
After looking at the documentation (NI-CAN Hardware and Software Manual, Section 4, Connectors and Cables), I told him that he might want to add, at a minimum, pin 3 - (V-) CAN reference ground. His lead told him that he did not need it since he was connecting both of the ports together. I know the correct solution is to just purchase a cable. This is not a production cable, just a 3 inch cable for him to learn the system, how to build cables, etc.
My question is what are the minimum pins that he needs to wire to the connector? The bus power (V+) is internal.
Thank you for any help especially with the cable issue.
Bill