triggering at a sine wave zero crossing using a PCI 6143

[asiri]

Hi,

I have a PCI 6143 card. I want to trigger at a zero crossing of a sine wave. Could you please give me some info to get started on this. Also I need to measure the rms half cycle voltage of a sine wave. what would be the best way to do this?

Thank you

Asiri

[GarPar]

Hi Asiri-

     The DAQmx Start Trigger (Analog Edge).vi starts an acquisition when an analog signal crosses a level that you specify.  It can be found from the functions palette under Measurement I/O»DAQmx»DAQmx Trigger.vi.

     You can also search for analog trigger examples on www.ni.com/community.  In addition, the Example Finder that launches with LabVIEW has hundreds of examples that can also assist you in getting started with your application.  In LabVIEW, click on Help»Find Examples.

     In terms of getting started with calculating RMS of a signal, check out this discussion forum post where the same issue is explored.  The RMS.vi might be the best way to get started with your measurements.  This VI can be found from the functions palette under Mathematics»Probability and Statistics.

     I hope this helps.  Best of luck with your application!