xiB & xiB-64 - Technical Manual Version 1.06
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4.3.2.1.
Triggered acquisition - single frame
Sensors support exposure overlapped with readout. When the trigger period (t
tper
) is longer than the exposure plus readout time,
exposure is not overlapped with readout. However when the trigger period is decreased, the sensor will expose the images in
overlap mode. In this case, the frame active signal will be constantly active. The trigger period has to be long enough so the
exposure of next frame does not end sooner than readout of previous frame.
Sensor timing in Exposure Overlapped with Data Readout Mode
figure 4-2, acquisition mode – triggered with overlap
Description:
t
eio
– Trigger (Digital Input) to Exposure Active (Digital Output)
t
exp
– Trigger (Digital Input) to start of exposure
t
exps
– Current Exposure Time set (XI_PRM_EXPOSURE)
t
fot
– Frame overhead time (FOT)
t
rd
– readout time (Readout Time)
t
row
– readout time of one row (Line period) depends on sensor settings
Conditions: Debounce on trigger input line and trigger delay are disabled.
The timing strongly depends on camera settings. Most of the times can be calculated using
Camera performance calculator.
The delay between trigger input and start of exposure:
𝑡
𝑒𝑥𝑝
= 𝑡
𝑠𝑒𝑛𝑠𝑑𝑒𝑙𝑎𝑦
+ 𝑡
𝑖𝑑𝑒𝑙𝑎𝑦
Where:
t
sensdelay
– Delay introduced by sensor itself. For most sensors the delay is constant.
Cameras with CMV50000 sensor have this time dependent on setting of the sensor. Namely it is line period and
bandwidth limit.
t
idelay
– Delay inside camera caused by internal electronics. This depends on input type.
Please refer to:
3.9.4 Optically isolated Digital Input
or
3.9.6 Non-isolated Digital Lines
The output signaling is then delayed the delay introduced from the output electronic.
𝑡
𝑒𝑖𝑜
= 𝑡
𝑒𝑥𝑝
+ 𝑡
𝑜𝑑𝑒𝑙𝑎𝑦
Where:
t
odelay
– Delay inside camera caused by internal electronics. This depends on output type.
Please refer to:
3.9.5 Optically isolated Digital Output
or
3.9.6 Non-isolated Digital Lines
For minimum trigger period (t
tper
) the following applies. The next trigger after one is processed needs to be applied so the end of
the triggered exposure does not overlap with the readout of the previous frame.
𝑡
𝑡𝑝𝑒𝑟
> max(𝑡
𝑟𝑑
, 𝑡
𝑒𝑥𝑝
) + 𝑡
𝑓𝑜𝑡
