Acquisition Monitoring Tools; Exposure Active Signal - Basler ace acA640-90gm User Manual

Image Acquisition Control

7.10 Acquisition Monitoring Tools

7.10.1 Exposure Active Signal

Exposure Active on Global Shutter Cameras (All Models Except the acA2500-14)
Cameras with a global shutter imaging sensor can provide an "exposure active" (ExpAc) output
signal. On these cameras, the signal goes high when the exposure time for each frame acquisition
begins and goes low when the exposure time ends as shown in Figure 57. This signal can be used
as a flash trigger and is also useful when you are operating a system where either the camera or
the object being imaged is movable. For example, assume that the camera is mounted on an arm
mechanism and that the mechanism can move the camera to view different portions of a product
assembly. Typically, you do not want the camera to move during exposure. In this case, you can
monitor the ExpAc signal to know when exposure is taking place and thus know when to avoid
moving the camera.
Exposure
Exposure
Frame N
ExpAc
Signal
Fig. 57: Exposure Active Signal on Cameras with a Global shutter
When you use the exposure active signal, be aware that there is a delay in the rise
and the fall of the signal in relation to the start and the end of exposure. See
Figure 57 for details.
110
Exposure
Frame N+1
2 µs to3.5 µs
10 µs to 26 µs
Exposure
Frame N+2
2 µs to 3.5 µs
10 µs to 26 µs
Timing charts are not drawn to scale
Times stated are typical
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