Chapter 3 Programming with NI-IMAQ
NI-IMAQ User Manual 3-10
©
National Instruments Corporation
High-Level Sequence Functions
Sequence functions include imgSequenceSetup,
imgSessionStartAcquisition and imgStopAcquisition. A
sequence initiates a variable-length and variable-delay transfer to multiple
buffers. You can configure the delay between acquisitions with
SequenceSetup and specify both the buffer list that will be used for
transfers and the number of buffers. After imgSequenceSetup, you can
monitor the status of the transfer and perform processing on any of the
buffers in the sequence or you can wait until the acquisition completes and
process all buffers simultaneously.
A sequence is appropriate for applications where you need to perform
processing on multiple images. You can configure a sequence to acquire
every frame or skip a variable number of frames between each image.
Figure 3 -4 illustrates a typical sequence programming order.
Figure 3-4. Sequence Programming Flowchart
imgInterfaceOpen imgInterfaceOpen opens
and configures the interface
according to the file setup by the
IMAQ Configuration Utility.
imgSessionStatus gives the current status of
the sequence, including the buffer number of the last buffer
that was successfully transferred. With this information,
you can determine which buffer you want to process.
imgSessionOpen opens a session that
will be used for all acquisition and configuration.
User-specific image processing.
imgClose closes the interface and session.
You must set up your buffer list and the
number of the frames/fields that need to
be skipped between each acquisition.
imgSessionOpen
Buffer list setup
imgSessionStatus
User-Specific Functions
imgSequenceSetup initiates a sequence to a
programmable number of buffers. These buffers can be
created either by the driver (using imgCreateBuffer
or passing a NULL) or by you.
imgSequenceSetup
imgClose
(Loop)
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