User`s manual
Basic Operation & Standard Features
BASLER A620
f 3-17
DRAFT
3.4 Trigger Ready Signal
As mentioned in Section 3.3.2, the start of exposure of a new frame must not occur until the
camera has completely finished readout of the previously captured frame. During normal
operation, the camera constantly monitors the state of the sensor and generates a “trigger ready”
(TrigRdy) signal. As shown in Figure 3-8, the trigger ready signal will go low when the exposure
of each frame is started and will go high when frame readout is complete and it is safe for the next
exposure to begin.
If you are triggering exposure with shot commands, a software trigger or and ExSync signal, you
can avoid over-triggering the camera by monitoring the TrigRdy signal and only triggering the
camera when the signal is high. (Over-triggering the camera means that you are attempting to
trigger image capture at a rate that is higher than the maximum allowed with the current camera
settings.)
You can ensure that you are operating the camera at the maximum allowed frame rate for the
current camera settings by monitoring the TrigRdy signal and immediately triggering image
capture each time you see the signal go high.
By default, the TrigRdy signal is assigned to physical output port 1 on the camera. See Section
2.5.2 for a description of the electrical characteristics of the camera’s physical output ports.
The assignment of the TrigRdy signal to a physical output port can be changed. See Section
6.7.10 for more information on changing the assignment of camera output signals to physical
output ports.
Figure 3-8: Trigger Ready Signal
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The trigger ready signal is not defined in the 1394 Trade Association Digital Camera
Specification. Trigger ready is a patented feature of Basler cameras that allows our
cameras to have optimized timings.
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If you attempt to start an exposure when the trigger ready signal is low, the camera
will delay the start of exposure until the next rise of the signal. This prevents you from
running the camera faster than the maximum rate and avoids dropping frames.
If the camera is in continuous shot mode and external triggering is disabled, the trig-
ger ready output signal will not be present.