Programming instructions

Chapter 6 One-Stop Single-Point Acquisition
LabVIEW Data Acquisition Basics Manual 6-4
© National Instruments Corporation
also offer more error handling control, more hardware functionality, and
efficiency in developing your application than the Easy VIs. You typically
use the Intermediate VIs to perform buffered acquisitions. You can read
more about buffered acquisitions in Chapter 7,
Buffering Your Way
through Waveform Acquisition
. The Intermediate Analog Input VI, AI
Single Scan VI, does multiple-channel, single-point acquisitions, as shown
in Figure 6-4.
Figure 6-4.
The AI Single Scan VI Help Diagram
The AI Single Scan VI returns one scan of data. You can also use this VI
to read only one point if you specify one channel. Use this VI only in
conjunction with the AI Config VI.
Figure 6-5 shows a simplified block diagram for non-buffered applications.
LabVIEW calls the AI Config VI, which configures the channels, selects
the
input limits
(the
high limit
and
low limit
inputs in the Easy VIs), and
generates a
taskID
. The program passes the
taskID
and the error cluster to
the AI Single Scan VI, which returns the data in an array (one point for each
channel specified).
Figure 6-5.
Using the Intermediate VIs for a Basic Non-Buffered Application
Figure 6-6 shows how you can program the AI Config and AI Single
Scan VIs to perform a series of single scans by using software timing
(a While Loop) and processing each scan. This example shows the
Cont Acquire&Chart (immediate) VI, which you can find in
labview\examples\daq\anlogin\anlogin.llb
.