Detect singnals crossing level

[astroboy]

Hi. I am creating a program that detects the 2 points of sinewave crossing zero DC levels, auto-stop at 2 points (ie, one cycle) and measure V peak.

So how do I do that? I don't want the program to continue measuring Vpeak over cycles or set the length of the measuring time. Because I will not know the frequency.

Thanks in advance

regards,

Clement

[Dennis_Knutson]

If all you want is Vmax, then you can use the Basic Trigger Detection function twice with different slopes to get a half cycle or the Basic Trigger Detection can be modified to return all (or a specific number) of trigger locations. In the attachment, is this modified VI (labVIEW 7.1). The returned trigger locations are used to determine the waveform subset and then the max is determined by the Array Min/Max function. 

[astroboy]

Hi Could you pls provide me your help priogram  in version 7.0.

Thanks. Sorry to trouble you.

 Clement