User`s guide

Controlling Logging Parameters

6-27

Acquiring 100 Frames

This example illustrates how you can specify the amount of data to be acquired and

determine how much data has been acquired. (For an example of configuring a time-

based acquisition, see “Acquiring 10 Seconds of Image Data” on page 7-5.)

Create an image acquisition object — This example creates a video input object

for a Windows image acquisition device. To run this example on your system, use the

imaqhwinfo function to get the object constructor for your image acquisition device

and substitute that syntax for the following code.

vid = videoinput('winvideo',1);

Configure properties — Specify the amount of data you want to acquire as the

number of frames per trigger. By default, a video input object acquires 10 frames per

trigger. For this example, set the value of this property to 100.

vid.FramesPerTrigger = 100

Start the image acquisition object -— Call the start function to start the image

acquisition object.

start(vid)

The object executes an immediate trigger and begins acquiring frames of data. To

verify if the video input object is logging data, use the islogging function.

islogging(vid)

ans =

The start function returns control to the command line immediately but the object

continues logging the data to the memory buffer. After acquiring the specified

number of frames, the object stops running and logging.

Check how many frames have been acquired — To verify that the

specified number of frames has been acquired, check the value of the

FramesAcquired property. Note that the object continuously updates the value of

the FramesAcquired property as the acquisition progresses. If you view the value of

this property several times during an acquisition, you can see the number of frames

acquired increase until logging stops.

vid.FramesAcquired

ans =