How to extract rise & fall times from DAQ square wave sig chs? Any Example vi's for this?

[johnnyc]

How can i extract rise & fall timing info from a buffered DAQ task containing 2 chs of square wave signals so i can then perform other calculations on? Any Example vi's for this app or similar app? My specific application is acquiring a square wave analog voltage input [on one ch] from a laser switch which is used to calculate "obstructed/present" or "not obstructed/not present" in terms of blocking or not blocking the laser beam's path to its receiver switch.  I'd like to calculate a velocity of the obstruction as it passes thru the beam extracting the rise and then fall time of ch#1's square wave that will be acquired in the event - velocity can be calculated by the obstruction's known length divided by the square wave's period.  Also, i'd like to compare the rise times on both channel's single square wave signals for other calculations.

I'd just like to find an Example vi to start from (if one exists) for this application or something similar.

Any guidance would be appreciated.

thanks,

John

(jac@arl.army.mil; 410-306-0739)

[Dennis_Knutson]

If you have at least the full version of LabVIEW, you can use the Transition Measurements function on the Analyze>Waveform Measurements palette. To get both rise and fall time, you just have to use it twice, each with a different polarity setting.