how to do triggering?

[pokyuk]

i try to do rising triggering in labview, but why the result is falling? anyone can help? is the ni device problem? or my block diagram problem? thanks

[Kyle_A.]

Hello,

What hardware are you using?  If you change the slope to rising do you get different results?  Can you try triggering without hysteresis to see if your results change as well?  Be sure to use a DAQmx Clear Task.vi at the end of your acquisition to clean up your resources used.

[pokyuk]

i can do the triggering, but how can i freeze (single trigger) the a period of waveform in 20ms for example? can give some idea of doing single triggering in labview8? thanks

[Kyle_A.]

Hi,

It sounds like you want to trigger your signal once, and capture 20 ms of data in that one trigger.  Since it sounds like you are able to take care of triggering, to get a single frame 20 ms long, you would need to look at your sampling rate and the samples taken.  For your code, you are using 1kHz sampling rate and 100 samples taken, which equivocates to 100ms (1000S/s divided by 100S = 100ms).  To get 20 ms of data, you need to only take 20 samples at 1kHz, or 200 samples at 10kHz, and so on.