Programming instructions

Chapter 7 Buffering Your Way through Waveform Acquisition
LabVIEW Data Acquisition Basics Manual 7-12
© National Instruments Corporation
where general value A is the
number of scans to read at a time
. Inside
the while loop, the Wait on Occurrence function sleeps in the background
until the chosen
DAQ Event
takes place. Notice that the timed out output
from the Wait on Occurrence function is wired to the selection terminal of
the case structure that encloses the AI Read VI. This means that AI Read
will not be called until the
number of scans to read at a time
have
been acquired. The result is that the while loop is effectively put to sleep,
because you do not try to read the data until you know it has been acquired.
This frees up processor time to do other tasks while you are waiting for
the DAQ Event. If the DAQ Occurrence times out, the timed out output
value would be TRUE, and AI Read would never be called. When your
acquisition is complete, DAQ Occurrence is called again to
clear all
occurrences
.
Figure 7-11.
Continuous Acq&Chart (Async Occurrence) VI
Circular-Buffered Analog Input Examples
The only differences between the simple-buffered applications and
circular-buffered applications in the block diagram is the
number of scans
to acquire
input of the AI Start VI is set to 0, and now we must call the