Acquisition Monitoring Tools; Exposure Active Signal - Basler acA2040-55 User Manual

AW00123409000
6.8

Acquisition Monitoring Tools

6.8.1

Exposure Active Signal

Exposure Active on Global Shutter Cameras (All Models Except the acA1920-25,
acA2500-14, acA3800-14, acA4600-10)
Cameras with a global shutter imaging sensor can provide an "exposure active" (ExpAc) output
signal. On these cameras, the high state of the signal indicates a logical one on the FPGA output
side (Figure 72, see also
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.
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
Using a GPIO line, set for output, will bring about shorter delays, compared to
using the opto-isolated output line. The exact delays depend on several factors
See Section 5.10.2 on page 88
Exposure
Exposure
Frame N
Opto-coupled OUT: 27 µs to 38 µs (Example Only)
GPIO OUT: <2.5 µs (Example Only)
ExpAc
Signal
Fig. 72: Exposure Active Signal on Cameras with a Global Shutter
Basler ace USB 3.0
Figure 41). This signal can be used as a flash trigger and is also useful
72).
Timing charts are not drawn to scale.
The times stated are only given as examples. They are only valid
for the operating conditions given in
for details.
Exposure
Frame N+1
Opto-coupled OUT: 3 µs to 6 µs (Example Only)
GPIO OUT: <0.5 µs (Example Only)
Image Acquisition Control
Exposure
Frame N+2
Section 5.10.3.
161