Basler Vision Technologies A202k, User Manual

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Operation and Features
BASLER A202
k
3-3
DRAFT
3.2 Exposure Time Control
The
A202
k
can operate under the control of an external sync signal (ExSync) or can operate in
“free-run”. In free-run, the camera generates its own internal control signal and does not require
an ExSync signal.
3.2.1 ExSync Controlled Operation
3.2.1.1 Basics of ExSync Controlled Operation
In ExSync operation, the camera’s frame rate and exposure time are controlled by an externally
generated (ExSync) signal. The ExSync signal is typically supplied to the camera by a frame
grabber board. You should refer to the manual supplied with your frame grabber board to
determine how to set up the ExSync signal that is being supplied to the camera.
When the camera is operating under the control of an ExSync signal, the length of the ExSync
signal period determines the camera’s frame rate. (Frame Rate = 1/ExSync Signal Period.)
Exsync can be periodic or non-periodic.
When the camera is operating with an ExSync signal, it has two modes of exposure time control
available: level-controlled mode and programmable mode.
• In ExSync, level-controlled mode, the exposure time is determined by the time between the
falling edge of ExSync and the next rising edge. The pixels are exposed and charge is accu-
mulated only when ExSync is low. The frame is read out and transferred on the rising edge of
the ExSync signal (see Figure 3-2).
Figure 3-2: ExSync, Level-controlled Mode
• In ExSync, programmable mode, the rising edge of ExSync triggers exposure and charge
accumulation for a pre-programmed period of time. The frame is read out and transferred at
the end of the pre-programmed period. The falling edge of ExSync is irrelevant (see Figure 3-
3). A parameter called "Timer 1" is used to set the length of the pre-programmed exposure
period.
Figure 3-3: ExSync, Programmable Mode