Where can documentation be found concerning the CAN (frames) message data in the FPGA format (an array of U32s)?

[William_Griffin]

I am trying to use a cRIO to communicate on a CAN bus. In particular, I want to send a CAN message from the FPGA using an invoke node. This node accepts an array of U32's, but I cannot find documentation concerning the data expected in each of elements.

Using the "Advanced CAN Frame to Channel Conversion Example" (http://zone.ni.com/devzone/cda/epd/p/id/5826) I have been able to reverse engineer the expected data, but this seems like a somewhat round about way to get to the information I am looking for.

Also, I have skimmed the "NI-CAN Hardware and Software Manual" (http://digital.ni.com/manuals.nsf/websearch/6C57190E7F6553A986257205006D273A) and I was unable to find this documentation. In all fairness, I did not read the entire 700 page manual, but I don't think that it should be necessary to read the entire thing to find the information I am looking for.

[DirkW]

If you install NI-RIO, this driver brings examples for the CAN modules as well. The examples should explain everything you need. You can find them here:

C:\Program Files\National Instruments\LabVIEW 8.x\examples\CompactRIO\Module Specific\NI 985x

The LabVIEW Help has the help topics for the CAN part included. Just open the LV Help and search for "9853".

DirkW

[pBerg]

Howdy William,

To sort of echo Dirk's response, if you're particularly curious about the format of the array of U32's and how it corresponds to a CAN frame, have a look at the CAN Convert Frame NI-CAN NI to 1D U32.vi that many of the 985x examples use. This subVI illustrates how to convert from a CAN cluster to an array of U32's. (This is located in labview\examples\nican\logfile.llb\CAN Convert Frame NI-CAN NI to 1D U32.vi). Here's a screenshot of its block diagram:




Message Edited by pBerg on 05-29-2008 12:07 PM

[Bob_Y.]

I think that William said that he had figured it out through examples, but was asking where the information was DOCUMENTED.  I am kind of wondering myself.  After I read the post, I looked at the manuals and the examples and there is a lot missing from the manuals. 

I think that the real question is about documentation and why we need to reverse engineer, not about the info.

Thanks,
Bob Young

[DirkW]

I agree that the help is somewhat hidden in our huge LabVIEW help document. However, it is there and can be found if you search for the right keyword.

Try to search for "9853 AND Input" and choose the "CAN Input Topic. If you scroll down this page you can find a detailed explanation for the cluster and array datatype.

The examples should show you then, how to use these datatypes.

An easier way to find the 985x help is to go to Start>>Programs>>National Instruments>>CompactRIO>>NI 9853

DirkW

[William_Griffin]

That was exactly the information I was looking so hard for. Thank you all for your help.