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Chapter 2 Basic Acquisition with NI-IMAQ for IEEE 1394 Cameras
NI-IMAQ for IEEE 1394 Cameras User Manual 2-4 ni.com
file opens, and all the user attributes are set in the driver. If no camera of the
same make and model is present, the Initialize function returns an error.
Camera Control Mode
The camera control mode parameter has two options: controller and
listener. The default option—controller—controls the camera and receives
video data. The listener only receives video data. Use the listener option in
broadcasting applications. Refer to the Broadcasting section of Chapter 3,
Advanced Programming with NI-IMAQ for IEEE 1394 Cameras, for more
information about broadcasting.
Configuration
After initializing the interface, configure the interface for acquisition by
specifying the following parameters: whether the acquisition is one-shot or
continuous, the number of internal buffers to use, and the region of interest
for the acquisition.
During configuration, the driver validates all the user-configurable
attributes. If any attributes are invalid or out of range, the driver returns an
error and does not configure the acquisition.
If you want to reconfigure the acquisition, call the Clear Acquisition
function before calling the Configure function again.
Note National Instruments recommends that you do not configure an acquisition in a loop
because doing so is time-intensive.
One-Shot/Continuous Acquisition
Use a one-shot acquisition to start an acquisition, perform the acquisition,
and stop the acquisition using a single function. The number of images
acquired is equal to the number of images in the images collection.
With a one-shot acquisition, you specify a certain number of internal
buffers. The camera transfers each image up to and including the specified
number of buffers. The driver acquires every image during a one-shot
acquisition. National Instruments recommends one-shot acquisition for
applications that do not require real-time acquisition or processing.
Use a continuous acquisition to start an acquisition, continuously acquire
images into the internal buffers, and explicitly stop the acquisition. With
continuous acquisition, the driver acquires video data continuously from