How do I stop acquiring a waveform when I've reached a known value?

[FMM]

I am currently using the acquire waveforms vi to read 30,000 samples of 3 channels at a sample rate of 20k during an engagement of a shaft. I would like to only acquire data until my output shaft reaches a known value. I would like to stop the acquisition when my shaft reaches the known speed. The problem is that I can see the engagement but I end up with some data of the shaft just running at a constant speed and I would like to use some of the waveform analysis vis on the engagement period. The shaft speed is one of the waveforms I am sampling. Is there an easy way to accomplish this?

[JedRetherford]

FMM,

The task that you are looking to accomplish should be a relatively easy task to accomplish by modifying some of the examples that ship with LabVIEW.

I have modified one of LabVIEW's shipping examples to stop when the input rises above 4.0 volts, and annotated the changes that I made on the block diagram. I believe that this should help you see one way of accomplishing the task that you are looking at.

I note that you did not mention the version of LabVIEW that you are using. I saved this example in LabVIEW 6.1, as it is the oldest version that I have on my computer.

I wish you the best of luck with your application.

Regards,
Jed R.
Applications Engineer
National Instruments