Chapter4 Programmingwith NI-IMAQ for 1394 VIs
©NationalInstruments Corporation 4-3 NI-IMAQfor IEEE-1394 Cameras User Manual
The most commonly used VIs are on the IMAQ for IEEE-1394 palette.
Youcan find VIs for basic acquisition and changing attributes.
The Motion and Vision»IMAQ for IEEE-1394»IMAQ Low Level
palette contains VIs for more advancedap plications.
See the NI-IMAQ for IEEE-1394 VI Reference help for more information.
Common NI-IMAQ for 1394 VI ParametersIMAQ1394 Session is a uniqueidentifier that specifies the Interface file
usedfor the acquisition. It is pro duced by the IMAQ1394 Init VI and used
asan in put to all other NI-IMAQ VIs. The NI-IMAQ for 1394 VIs use
IMAQ1394Session Out, which is identical to IMAQ Session, to s implify
dataflowprogramming. IMAQ1394 Session Out is similar to the d uplicate
file sessions provided by the file I/O VIs. The high-level acquisition
VIs—IMAQ1394 Snap, IMAQ1394 Grab Setup, and IMAQ1394
Sequence—requireyou to wire IMAQ1394 Session In only if you are
using an interface other than the default cam0, if you are using multiple
cameras,or if you need to set IMAQ 1394 properties before theacquisition.
Manyacquisition VIs require that you supply an image buffer to receive the
capturedimage. You can create this image bufferwith the IMAQ Create VI.
Consultthe Buffer Management section of this chapter for more
information. The input that receivesthe im age bufferis Image in.The
Image outout put returns the captured image.
The acquisition VIs use the Region of Interest input to specify a
rectangularportion o f an image frame to be captured. Youcan use Region
ofInterest to reduce th es ize of the image you want to capture. Region of
Interestis an array of four elements with the elements defined as Left, Top,
Right, Bottom. If Region of Interest is not wired, the entire image
acquisition window is captured. Youconfigure the default acquisition
windowusing MAX.
Note TheRegionofInterestinputisonlyusedwhenyourcameraisconfiguredtouse
Scalable Image Format(format 7).