User`s manual

Operation and Features
BASLER A101
f 3-7
DRAFT
Case 2 - Exposure Start When the Camera is Transferring a Frame
After each exposure is complete, there is a time period of 80.7 ms. during which the captured
frame is transferred from the CCD sensor to the camera’s image buffer.
If the ExTrig signal rises during this time period as shown in Figure 3-4:
• The start of exposure will occur between 3 µs and 86 µs after the rise of ExTrig. The delay in
the start of exposure will vary from frame to frame but will always fall in the 3 to 86 µs range.
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• The IntEn signal will rise between 2 and 3 µs after the start of exposure. For a given camera,
the delay in the rise of IntEn will be consistent from frame to frame. (The size of the delay will
vary slightly from camera to camera, but will always be in the 2 to 3 µs range.)
• The actual length of exposure will be equal to the programmed exposure time plus 4 µs.
To know when frame transfer to the buffer is taking place, the user must monitor the integrate
enabled signal. The frame transfer time period begins on the falling edge of the integrate enabled
signal and lasts for 80.7 ms.
Figure 3-4: Exposure Start During Frame Transfer
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This variability in the start of exposure is commonly referred to as an exposure start jitter. It
occurs because when the camera is transferring an image, exposure can only start at certain
fixed points during the frame transfer process. If an exposure is triggered when the transfer
process is very near to one of these fixed points, the exposure start delay can be as little as 3
µs. If an exposure is triggered when the transfer process is very far from one of these fixed
points, the start delay can be as much as 86 µs.
If you need very close control of exposure start time, you should trigger exposure start when the
camera is not transferring a frame as shown on page 3-6.
*
The camera can be programmed to react to a rising edge of the ExTrig signal or to a
falling edge of the ExTrig signal. We strongly recommend that you program the cam-
era to react to the rising edge of the signal (i.e., active high).
If falling edge triggering is used, the time between the falling edge of the ExTrig signal
and the start of exposure will be excessively long (at least 90 µs). This occurs due to
the characteristics of the opto-coupler on the camera’s ExTrig input.
TrigRdy
ExTrig
Exposure
IntEn
Frame
Transfer
3 µs
80.7 ms
Frame N Transfer to the Image Buffer
Exposure
Frame N
Exposure
Frame N + 1
Exposure
Frame N + 2
80.7 ms
Frame N + 1 Transfer to the Image Buffer
TIMING CHARTS ARE NOT DRAWN TO SCALE
86 µs
2 µs
3 µs
3 µs
86 µs
2 µs
3 µs
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