Chapter 3
Programming with NI-IMAQ
3-6
©
National Instruments Corporation
Figure 3-1 illustrates the values of the signals during a three-buffer
sequence acquisition.
Figure 3-1.
NI-IMAQ Status Signals
You can use the NI-IMAQ status signals for many purposes. Pulses can be
generated based on the assertion of any of these signals. This allows you to
generate specific timing pulses based on acquisitions to control other
aspects of your system, such as a strobe light. Furthermore, you can
configure callback functions that are invoked based on any of these signals.
For example, you may want to initiate an image processing routine as soon
as an image is in memory. You can configure a callback containing image
processing code to be invoked when Buffer Complete is asserted.
Introductory Programming Examples
This section introduces some examples for performing the different types
of image acquisition. The error codes that NI-IMAQ returns are not
included in the examples. In your programs, always check the return code
for errors.
Note
You can find these code examples in the
ni-imaq\samples
directory.
AQ_IN_PROGRESS
FRAME_START
FRAME_DONE
BUF_COMPLETE
AQ_DONE
Board Initiates
Acquisition
Board Initiates
Acquisition
All Image
Data In
Memory
All Image
Data In
Memory
Last Valid
Pixel Acquired
By Board
Buffer 0
Data In
Memory
First Valid
Pixel Acquired
By Board
Buffer 1
Data In
Memory
Buffer 2
Data In
Memory
UM.book Page 6 Monday, July 13, 1998 9:49 AM
