Dalsa PC2-CamLink, Руководство пользователя

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Part I: PC2-CamLink Board PC2-CamLink User's Manual
Area Scan Triggers
The External Trigger allows image acquisition to be synchronized to external events. When acquiring
an image in External Trigger mode, the acquisition will not start until the PC2-CamLink receives a
trigger signal. Acquisition begins with the next valid frame after the trigger.
A variety of trigger events can fire the EXSYNC and PRIN pulse generators for area scan cameras. All
trigger sources share the following parameters:
•
Trigger polarity
•
Trigger signal debounce
•
Number of frames captured for each trigger
Trigger polarity can take four possible values:
Rising Edge
The rising edge of the trigger source fires the total of the specified number of frames
captured.
Falling Edge The falling edge of the trigger source fires the total of the specified number of frames
captured.
Active High
Frames are captured as long as the trigger source is active high on the rising edge of
FVAL.
Active Low Frames are captured as long as the trigger source is active low on the rising edge of
FVAL.
The incoming trigger pulse is passed through a debounce circuit” to ensure that no glitch would be
detected as a valid trigger pulse. This can be programmed from 0
μ
s to 255
μ
s. Any pulse smaller than
the programmed value will be blocked and therefore not seen by the acquisition circuitry. Note that the
debounce circuit introduces a delay in an external trigger detection. Therefore, if a period of 255
μ
s is
selected, the actual trigger detection will be forwarded 255
μ
s after the first edge of the trigger pulse
(assuming a stable pulse of more than 255
μ
s).
Debouncer
0..255 us
t(d)
External Trigger
t(et)
Validated Trigger
t(vt) = t(et) - t(d)
Figure 5: External Trigger