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viewing events -凯发k8网页登录

events occur during an acquisition at a particular time when a condition is met. these events include:

  • error

  • framesacquired

  • start

  • stop

  • timer

  • trigger

all acquisitions consist of at least 3 events:

  • starting the device

  • triggering the device

  • stopping the device.

executing an acquisition

initiate a basic acquisition using a video input object.

% access an image acquisition device.
vidobj = videoinput('winvideo', 1);
% use a manual trigger to initiate data logging.
triggerconfig(vidobj, 'manual');
% start the acquisition.
start(vidobj)
% trigger the object to start logging and allow the acquisition to run for
% couple of seconds.
trigger(vidobj)
pause(2);
% stop the acquisition
stop(vidobj)

viewing event information

to view event information for the acquisition, access the eventlog property of the video input object. events are recorded in chronological order. 

% view the event log.
events = vidobj.eventlog

events = 
1x3 struct array with fields:
    type
    data

each event provides information on the state of the object at the time the event occurred.

% display first event.
event1 = events(1)

event1 = 
    type: 'start'
    data: [1x1 struct]

data1 = events(1).data

data1 = 
             abstime: [2005 6 5 23 53 14.1680]
    framememorylimit: 341692416
     framememoryused: 0
         framenumber: 0
       relativeframe: 0
        triggerindex: 0

% display second event.
event2 = events(2)

event2 = 
    type: 'trigger'
    data: [1x1 struct]

data2 = events(2).data

data2 = 
             abstime: [2005 6 5 23 53 14.7630]
    framememorylimit: 341692416
     framememoryused: 0
         framenumber: 0
       relativeframe: 0
        triggerindex: 1

% display third event.
event3 = events(3)

event3 = 
    type: 'stop'
    data: [1x1 struct]

data3 = events(3).data

data3 = 
             abstime: [2005 6 5 23 53 16.9970]
    framememorylimit: 341692416
     framememoryused: 768000
         framenumber: 5
       relativeframe: 5
        triggerindex: 1

% once the video input object is no longer needed, delete
% it and clear it from the workspace.
delete(vidobj)
clear vidobj
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