ncGetTimer returning OS time with USB-8473?

[dkfire]

I have a opservation I would like to have confirmed.

When using the ncGetTimer from the CAN Frame API with a NI-CAN USB-8473 I get the OS timestamp in second, and NOT the 8473 timer value. This give me a very bad resolution, as the OS resolution is only a little under 16 ms.

Can it really be that the ncGetTimer.vi return the OS time and not the time on the card ? or is it a limitation on the USB-8473 ?

I have done a simple example:

And from a run with this, it is clear that ncGetTimer.vi is not returning the timer value from the card, but for the OS.

If this is want to expect from this .vi, then the help should be updated with this kind of limitation.

[A.Rohde]

Hi dkfire

Thank you for the detailed description of your observations. The following KnowledBase describe what NI-CAN API functions are supported by the NI USB-847x;

Which NI-CAN Frame API Functions does the NI USB-847x Device Support?

http://digital.ni.com/public.nsf/allkb/E1A44077DA6C819186257288006B76D7?OpenDocument

From the article please note that the ncGetTimer.vi is not supported by your USB-8473, and that is why you will find the behavior different than described in the help file.

Best regards 

Anders Rohde

Applications Engineer

National Instruments Denmark