Programming instructions

Chapter 7 Buffering Your Way through Waveform Acquisition
© National Instruments Corporation 7-7 LabVIEW Data Acquisition Basics Manual
Simple-Buffered Analog Input with Multiple Starts
In some cases, you might not want to acquire contiguous data, like in an
oscilloscope application. In this case, you would only want to take a
specified number of samples as a snapshot of what the input looks like
periodically. For an example using the Intermediate VIs, open the Acquire
N-Multi-Start VI found in
labview\examples\daq\anlogin\
anlogin.llb
. The Acquire N-Multi-Start VI, shown in Figure 7-7, is
similar to the Acquire N Scans example, except the acquisition only occurs
each time the start button on the front panel is pressed.
Figure 7-7.
Taking a Specified Number of Samples with the Intermediate VIs
This example is similar to the standard simple buffered analog input VI, but
now both the AI Start and AI Read VIs are in a While Loop, which means
the program takes a number of samples every time the While Loop iterates.
Note
The AI Read VI returns 1,000 samples, taken at 5,000 samples per second, every
time the While Loop iterates; however, the duration of the iterations of the While
Loop can vary greatly. This means that, with this VI, you can control the rate at
which samples are taken, but you may not be able to designate exactly when your
application starts acquiring each set of data. If this start-up timing is important to