Asynchronous Trigger Settings; Figure 6.6: Software Trigger Timing - Point Grey Flea3 FL3-U3 Technical Reference Manual

Point Grey Flea3 USB 3.0 Technical Reference
The time from when the software trigger is written on the camera to when the start of integration occurs can only be
approximated. The average time from register write request to register write response is approximately 49.85 us. The
"write success" response is only sent from the camera to the host system once the internal trigger pulse is initiated.
We then add the trigger latency (time from the trigger pulse to the start of integration) to this, which is approximately
6 us for a camera capturing 640x480 images. Therefore, the total time from when the register is written to the start of
integration is approximately 56 us.
6.4.10

Asynchronous Trigger Settings

For information about working with the trigger registers in your FlyCapture application, refer to the AsyncTriggerEx
sample program, available with the FlyCapture SDK.
Trigger Mode—This controls the trigger mode. When trigger mode is enabled, frame rate is changed from Auto to Off
state. This change affects the maximum shutter time
Off state.
Trigger Delay—This provides control over the time delay, depending on the current mode:
In Asynchronous trigger mode: controls the delay between the trigger event and the start of integration
n
(shutter open).
In Free-running mode: controls the synchronization offset of the camera relative to normal synchronization.
n
This is useful for offsetting image acquisition between automatically synchronized cameras. (Not applicable to
GigE Vision or USB cameras.)
Software Trigger—This allows the user to generate a software asynchronous trigger.
Revised 9/27/2012
Copyright ©2011-2012 Point Grey Research Inc.

Figure 6.6: Software trigger timing

This timing is solely from the camera perspective. It is virtually impossible
to predict timing from the user perspective due to latencies in the
processing of commands on the host PC.
On FL3-U3-13Y3 a software trigger cannot be used for Trigger Mode 1.
(page 111). If trigger mode is disabled, frame rate remains in the
6 Image Acquisition
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