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8.Features
© 2023 China Daheng Group, Inc. Beijing Image Vision Technology Branch 112
If rising edge triggering is enabled, exposure starts when the trigger signal rises and continue until the
trigger signal falls, as shown in Figure 8-28
Exposure
Hardware trigger signal
Figure 8-28 The sequence diagram in rising edge trigger of TriggerWidth exposure mode
If falling edge triggering is enabled, exposure starts when the trigger signal falls and continue until the
trigger signal rises, as shown in Figure 8-29
Exposure
Hardware trigger signal
Figure 8-29 The sequence diagram in falling edge trigger of TriggerWidth exposure mode
Avoid overtriggering in TriggerWidth exposure mode. If the TriggerWidth exposure mode is enabled, do
not send trigger signals at too high a rate. Otherwise, trigger signals will be ignored, and a
FrameStartOvertrigger event will be generated.
The Exposure Overlap Time Max feature can optimize the acquisition of overlapping images. This
parameter is especially useful if the user wants to maximize the camera's frame rate, i.e., if the user wants
to trigger at the highest rate possible.
Prerequisites
a)
Set the TriggerMode parameter to On.
b)
Set the TriggerSource parameter to one of the available hardware trigger source, e.g., Line0.
c)
Set the ExposureMode parameter to TriggerWidth exposure mode.
How it works
The user can use overlapping image acquisition to increase the frame rate of the camera. With overlapping
image acquisition, the exposure of a new image begins while the camera is still reading out the sensor
data of the previous image.
In TriggerWidth exposure mode, the camera does not "know" how long the image will be exposed before
the trigger period is complete. Therefore, the camera cannot fully optimize overlapping image acquisition.
To avoid this problem, the user can enter a value for the ExposureOverlapTimeMax parameter, which
represents the shortest exposure time the user intends to use (in µs). This helps the camera optimize the
overlapping image acquisition.