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Obtain exclusive use of image acquisition device




start(obj) obtains exclusive use of the image acquisition device associated with the video input object obj and locks the device's configuration. Starting an object is a necessary first step to acquire image data, but it does not control when data is logged.

obj can either be a 1-by-1 video input object or an array of video input objects.

Data logging is controlled with the TriggerType property.

Trigger Type

Logging Behavior


Data logging occurs when the condition specified in the object's TriggerCondition property is met via the TriggerSource.


Data logging occurs immediately.


Data logging occurs when the trigger function is called.

Use the triggerconfig function to configure the object's trigger settings.

When an acquisition is started, obj performs the following operations:

  1. Transfers the object's configuration to the associated hardware.

  2. Executes the object's StartFcn callback.

  3. Sets the object's Running property to 'On'.

If the object's StartFcn errors, the hardware is never started and the object's Running property remains 'Off'.

The start event is recorded in the object's EventLog property.

An image acquisition object stops running when one of the following conditions is met:

  • The stop function is issued.

  • The requested number of frames is acquired. This occurs when

    FramesAcquired = FramesPerTrigger * (TriggerRepeat + 1)

    where FramesAcquired, FramesPerTrigger, and TriggerRepeat are properties of the video input object.

  • A run-time error occurs.

  • The object's Timeout value is reached.


The start function can be called by a video input object's event callback.

obj.StopFcn = {'start'};

Version History

Introduced before R2006a