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.
Solved! Go to Solution.
please keep in mind that the 8512 is the new NI-XNET device, therefor you ll need to check the NI-XNET User Manual for further assistance.
NI-XNET one and two-port boards include two LEDs per port to help you monitor hardware and bus status. LED 1 primarily indicates whether the
hardware is currently in use. LED 2 primarily indicates the activity information of the connected bus.
refer chapter 3-16 of the NIXNET manual for further details
2) connector: see chapter 3-11 for the pinouts
for loop back testing a wiring from CAN H to CAN H as well as CAN L to CAN L should be sufficient.
High-Speed CAN networks are typically terminated on the bus itself instead of within a node.
However, NI-XNET allows you to configure termination within the node to simplify testing.
If your bus already has the correct amount of termination, leave this property in the default
state of Off. However, if you require termination, set this property to On.
refer chapter 3-4 as well which explains the High Speed Layer in Details