Extract SPN for a signal from a .dbc using XNET API

[labviewman]

This morning I looked at using XNET to load a CAN bus (J1939) .dbc file where I would parse frames, signals, signal SPNs, and misc signal details. I was successful except I just can't figure out how to extract the SPN for a signal. Seems like I am just a few clicks away but I'm having no luck.

Any one have an idea how this is done?

Thanks,

Todd

[DiegoH214]

Hello Labviewman,

Please check this thread. 

https://forums.ni.com/t5/LabVIEW/Diagnostic-Messages-J1939/td-p/2157174

Diego H

National Instruments

[labviewman]

Thanks, but that doesn't help.

[JefeL]

Unfortunately J1939 with XNET does not currently offer the capability to extract the SPN from the signal information contained in the database.

[labviewman]

Since it doesn't look like this is possible via the XNET API, I figured out the .dbc database structure for the SPNs (signal names). 

The line I look for is structured like this:

BA_ "SPN" SIG_ XXXX SPNname SPNNumber;

I look for '"SPN" SIG_' and parse the rest (XXXX is a cross reference to the PGN/message name).  If no error, I add the SPNname and SPNNumber to the 'SPN found' arrays.  Then, since I already know the SPNnames for the signals in the database via the XNET Database vis, I search the created array (SPN name found array), take the index to the found name and index the SPNNumber array for the SPN/signal number.

The above method found 97% of the SPN numbers for the SPNnames found with the XNET database vis.  I checked about 10 of the 3% that were not found...they didn't have a SPN/signal number, so it seems my method works.