Basler A202k User Manual download pdf (Page 33)

Operation and Features

BASLER A202

k 3-3

DRAFT

3.2 Exposure Time Control

The A202k 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

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Basler A202k User Manual Page 33