GigE VA Series User Manual page 25

VA GigE series
Applying Trigger Signals
The paragraphs above mention "applying a trigger signal". There are two ways to apply an exposure start trigger
signal to the camera: via software or via external (commonly referred to as hardware).
To apply trigger signals via Software, you must set the Trigger Source parameter to Software. At that point,
each time a Trigger Software command is executed, the exposure start trigger signal will be applied to the
camera.
To apply trigger signals via External, you must set the Trigger Source parameter to External. At that point,
each time a proper electrical signal is applied to the camera, an occurrence of the exposure start trigger signal
will be recognized by the camera.
Exposure Time Control
When an exposure start trigger signal is applied to the camera, the camera will begin to acquire a frame.
A critical aspect of frame acquisition is how long the pixels in the camera's sensor will be exposed to light during
the frame acquisition.
If the Trigger Source parameter is set to Software, a parameter called the Exposure Time will determine the
exposure time for each frame. At this point, you must set the Exposure Mode parameter to Timed.
If the Trigger Source parameter is set to External, there are two modes of operation: Timed and Trigger Width.
With the Timed mode, the Exposure Time parameter will determine the exposure time for each frame.
With the Trigger Width mode, the way that you manipulate the rise and fall of the external signal will determine
the exposure time. The Trigger Width mode is especially useful if you want to change the exposure time from
frame to frame.
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