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start

Obtain exclusive use of image acquisition device

Syntax

start(obj)

Description

start(obj)obtains exclusive use of the image acquisition device associated with the video input objectobjand 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.

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

Data logging is controlled with theTriggerTypeproperty.

Trigger Type

Logging Behavior

'hardware'

Data logging occurs when the condition specified in the object'sTriggerConditionproperty is met via theTriggerSource.

'immediate'

Data logging occurs immediately.

“手动”

Data logging occurs when thetriggerfunction is called.

Use thetriggerconfigfunction to configure the object's trigger settings.

When an acquisition is started,objperforms the following operations:

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

  2. Executes the object'sStartFcncallback.

  3. Sets the object'sRunningproperty to'On'.

If the object'sStartFcnerrors, the hardware is never started and the object'sRunningproperty remains'Off'.

The start event is recorded in the object's事件日志property.

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

  • Thestopfunction is issued.

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

    FramesAcquired = FramesPerTrigger * (TriggerRepeat + 1)

    whereFramesAcquired,FramesPerTrigger, andTriggerRepeatare properties of the video input object.

  • A run-time error occurs.

  • The object'sTimeoutvalue is reached.

Examples

Thestartfunction can be called by a video input object's event callback.

obj.StopFcn = {'start'};

版本历史

Introduced before R2006a

See Also

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