waveform timestamps

[cviuser167]

Greetings, All.

What is the source and accuracy of the timestamp in the waveform data structure if it is acquired with the AI Read function from a DAQ card (PCI-6036E)?

The PC clock? Something internal that is initially set to the PC clock?

I'm trying to sync my collected AI data to a signal that is collected via a serial input in a parallel loop. I have set up the AI data to be 2x the frequency of the streaming serial data.

Using LabVIEW 6.1.

Thanks-
-dennis.

[AlanArmstead]

Dennis-
Yes, the timestamp is taken from the PC system time. So it will only be as accurate as the OS allows it to be (due to time slicing, thread scheduling, etc). Also, it is only in seconds, so you won't be able to get very precise times. If you need accurate analog input data, you should set up your program to acquire hardware timed data. The scan clock of the DAQ device is very accurate. FYI, you can check the specs of your board here:
http://www.ni.com/pdf/products/us/4daqsc202-204_ETCx2_212_213.pdf
Hope this helps.
-Alan A.