Triggered aquisition for determined time

Question

I am using a PCI-6371 to trigger a continuous AI aquisition on 8 channels of a NI-4472 at 15 ks/s, while displaying and writing the data to a file. I am currently using the get date/time in seconds function to determine when to exit the loop, but the time is not accurate enough. I need to aquire data for a pre-determined amount of time with a high degree of accuracy. Is there a way to set up a timed AI aquisition as opposed to continuous in a loop, while maintaining the display and file writing aspects?

Answer 1

Dave,
I don't have a particular example here, but looking at the shipping example you mentioned, here's a couple quick things to try:
1. Increase your buffer size from the 2500 scan default. Give yourself a few seconds worth of buffer, say 4 seconds worth for a size of 60000.
2. Increase the # of scans to read (& display & file) at a time. The minimum I'd bother trying is 500, which would correspond to updating your chart 30 times a second. You may find you need to increase it from there however.
Operating on larger chunks of data less frequently lowers the fraction of overhead cost such as formatting to spreadsheet string, updating chart.
3. Consider writing to a binary file so you don't have to convert all that data
into a string format before writing to file.
Hope these ideas are enough to get a trial version running for you.
-Kevin P.