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Exposure Defined by Trigger Pulse Length


This feature allows the control of the exposure length with the input trigger pulse.
This functionality is analogous with the bulb exposure mode used in common photography.

The sensor is exposing between the rising and the falling edge in case of:
XI_PRM_TRG_SOURCE = XI_TRG_EDGE_RISING

Or between the falling and the rising edge of the input trigger pulse in case of:
XI_PRM_TRG_SOURCE = XI_TRG_EDGE_FALLING
The exposure length can be controlled also in software trigger mode using the parameter:
XI_PRM_TRG_SOFTWARE = 1 as the start of exposure

XI_PRM_TRG_SOFTWARE = 0 as the end of exposure

Behavior on Start Acquisition

When trigger is active (e.g. level high when XI_TRG_EDGE_RISING) while xiStartAquisition, the exposure starts immediately without waiting for the first edge. Similarly the exposure stops on xiStopAquisition even if trigger is still active.

Timing Diagram

Timing when the rising edge of the trigger pulse is starting the exposure.
XI_PRM_TRG_SOURCE = XI_TRG_EDGE_RISING


Timing when the falling edge of the trigger pulse is starting the exposure.
XI_PRM_TRG_SOURCE = XI_TRG_EDGE_FALLING

Feature parameters

xiApi parameters

Feature related parameters
XI_PRM_TRG_SOURCE = XI_TRG_SOFTWARE / XI_TRG_EDGE_RISING / XI_TRG_EDGE_FALLING
XI_PRM_TRG_SELECTOR = XI_TRG_SEL_EXPOSURE_ACTIVE
XI_PRM_ACQ_TIMING_MODE = XI_ACQ_TIMING_MODE_FREE_RUN

GenICam reference (SFNC)

TriggerSelector = ExposureActive

Sample code

  
// set acquisition mode
xiSetParamInt(h,XI_PRM_ACQ_TIMING_MODE,XI_ACQ_TIMING_MODE_FREE_RUN);
// set GPI used as trigger
xiSetParamInt(h,XI_PRM_GPI_MODE,XI_GPI_TRIGGER);
// set trigger source
xiSetParamInt(h,XI_PRM_TRG_SOURCE,XI_TRG_EDGE_RISING);
// set trigger selector
xiSetParamInt(h,XI_PRM_TRG_SELECTOR,XI_TRG_SEL_EXPOSURE_ACTIVE);
//start acquisition
xiStartAcquisition(h);

Note: The order of parameters setting is not mandatory

Cameras supporting this feature

List of cameras with firmware and software where this feature is supported

camera families
xiQ
xiC
xiB
xiX
xiT

Note: Camera models MQ013xG-E2 do not support this feature since sensor timing is not supporting this functionality.