CAN 8461/2 high baudrate

[Ryan Starn]

While using the Basic Frame CAN Receive Example VI, the program will not function when a baud rate is set above 125k, but will work for lower acceptable baud rates. We are attempting to read information off a CAN network that is 500k. We had attempted to connect to the other network using the example VI, but got no response. We then attempted to send data from one port to the other and found that raising the baudrate above 125k did not work. There is probably a simple explanation or work around and we would appreciate any help.

Thanks,

Ryan

[biker2000]

Hi Ryan,

Did you terminate your network correctly? A high-speed CAN network needs to be terminated with 120 ohms at each end of the CAN cable. Without proper termination effects like the one you are observing are very common.

-B2k

[Ryan Starn]

We have terminated both ends of the connections and still have had no data come through when operating above 125k.

[biker2000]

Hi Ryan,

What type of NI CAN hardware are you using?

-B2k

[Ryan Starn]

the card is a NI-PXI-8461 Series 2, 2 port (http://sine.ni.com/nips/cds/view/p/lang/en/nid/3504) and the PXI is a 1000B with ni pxi 8186 embedded controller (http://sine.ni.com/nips/cds/view/p/lang/en/nid/3504).

The software we are using is Labview 7.1

We are using a laptop with windows xp ethernet connected to the pxi. 

[biker2000]

Hi Ryan,

Are there any warnings (not errors) occurring? LabVIEW’s Simple Error handler VI does not indicate warnings, but one can look at the error cluster directly (see attached VI).

Before you run your application, launch NI Spy (Start » Programs » National Instruments), make sure that the NI-CAN API is monitored (Spy » Options… » View Selections) and start the capture. Now run your application. NI Spy is now logging all calls to the NI-CAN driver including the status of those calls. When your application reports the error, stop NI Spy and save the capture to a file (File » Save).
As NI Spy captures all calls to any CAN card in the system, it will log the calls from the transmitter as well as from the receiver (CAN Receive.vi example).

Does using the BusMonitor (right-click on the receiving port of the CAN card in the Measurement and Automation and select ‘BusMonitor’) instead of the CAN Receive.vi example change anything?

-B2k

[Ryan Starn]

The NI-Spy does not capture any information coming from the pxi, and the can.receive program you sent does not show any errors or warnings. In addition, the MAX does not show individual ports under the can card and does not allow bus monitoring. (It is possible that I'm looking in the wrong location "Remote System/PXI/Devices and Interfaces/PXI System/Chassis 1/CAN") .

Thanks for your help

[biker2000]

Hi Ryan,

I somehow missed that you’re using the PXI system as a LabVIEW Real-Time target. You are right, neither NI Spy nor the BusMonitor does work in the LabVIEW Real-Time environment.

Can you cable both ports together and run the attached VI? The VI switches through different baud rates and stops if the transmission fails. Does the error cluster indicate any warning or error (‘code’ <> 0)?

-B2k

[Ryan Starn]

We seem to be geeting an error when we run this VI.

[biker2000]

Seems like I forgot to make the current values default. Could you run the updated VI again? I'm interested at what baud rate the VI fails.

BTW: What version of the NI-CAN driver are you using?

-B2k