I have asked this question a little differently before and got some answers.
I want to have a button that the user can click and start acquiring data. So my labview is working and at time T the user clicks and the data will be collected to be processed.
I have been told that I can collect the data from the beginning and then use extraction portion of the signal. But for some reasons it has its own problems. I was wondering if anybody know any way that the data acquisition can start manually. (my labview should be working and I am sending some analog output at time 0. Just the analog input should be collected by demand.)
Here is an idea:
1. Create your tasks for AI Read
2. Set Sampling Clok to Finite Samples
3. Use an Event Structure. Add an Event Value Changed - Button "Start Acquisition". In this event tab you'll:
3.1 Start task (not necessary in daqmx 9.1)
3.2 Read Samples - same number as defined in 2.
3.3 Stop task (not necessary in daqmx 9.1)
3.4 Process data or whatever
Just for the record, I have been told by one of the NI support group that I can use case structure and put my DAQ assistant/processing data in that, and have a push button wired to case structure to start acquiring data leave the false part of case structure empty. That worked.