Synchronizing two 8513

[remllov]

Hey,

i'm working with a PXI-1033 with three PXI Cards. 1 x NI PXI-6229 an 2 x NI-PXI-8513/2.

Currently I try to read a CAN Signal with the two CAN Cards. The CAN wire is send by an external ECU and is connected to the Cards. Now my problem is, that the Timestamp is not the same. I already looked at the NI Example for synchonizing two CAN Cards. Later on the two CAN Cards should also be synched with the DAQ Card.

What can I do to sync the timestamps?

Thanks in advance!

[reschri]

Hi!

The Timestamp is something coming from the Operating System not from the measurement Hardware itself. You can have the effect, that you have two DAQ-Task hardware triggered and aquiring exactly in synch, but they have differing timestamps when putting them out as waveforms with absolute time.

http://digital.ni.com/public.nsf/allkb/5D42CCB17A70A06686256DBA007C5EEA

The timestamp is calculated relativly to the calls to the driver API - Windows "tells" what date it is. They are not as accurated as the I/O itself.

Real hardware Sychronsisation is done over Triggering/Sychronization-functionality, the Windows created timestamps will never have that accuracy.

In your case, I would ignore the "absolute" value and look only on the relative time passed. You can have LabVIEW create one absolute time stanp at the beginn of measurement, which cann serve as your absolute fix point.

Regards

René