Acquisition Timing Chart - Basler ace acA640-90gm User Manual

7.11 Acquisition Timing Chart

Figure 65 shows a timing chart for frame acquisition and transmission. The chart assumes that
exposure is triggered by an externally generated frame start trigger (ExFSTrig) signal with rising
edge activation and that the camera is set for the timed exposure mode.
As Figure 65 shows, there is a slight delay between the rise of the ExFSTrig signal and the start of
exposure. After the exposure time for a frame acquisition is complete, the camera begins reading
out the acquired frame data from the imaging sensor into a buffer in the camera. When the camera
has determined that a sufficient amount of frame data has accumulated in the buffer, it will begin
transmitting the data from the camera to the host PC.
This buffering technique avoids the need to exactly synchronize the clock used for sensor readout
with the data transmission over your Ethernet network. The camera will begin transmitting data
when it has determined that it can safely do so without over-running or under-running the buffer.
This buffering technique is also an important element in achieving the highest possible frame rate
with the best image quality.
The exposure start delay is the amount of time between the point where the trigger signal
transitions and the point where exposure actually begins.
The frame readout time is the amount of time it takes to read out the data for an acquired frame
(or for the acA750, an acquired field) from the imaging sensor into the frame buffer.
The frame transmission time is the amount of time it takes to transmit an acquired frame from the
buffer in the camera to the host PC via the network.
The transmission start delay is the amount of time between the point where the camera begins
reading out the acquired frame data from the sensor to the point where it begins transmitting the
data for the acquired frame from the buffer to the host PC.
The exposure start delay varies from camera model to camera model. The table below shows the
exposure start delay for each camera model:
Camera Model
acA640-90gm/gc
acA640-100gm/gc
acA750-30gm/gc
acA1300-30gm/gc
acA1600-20gm/gc
acA2500-14gm/gc
Table 9: Exposure Start Delays
Note that, if the debouncer feature is used, the debouncer setting for the input line must be added
to the exposure start delays shown in Table 9 to determine the total start delay. For example,
assume that you are using an acA640-100 camera and that you have set the cameras for hardware
triggering. Also assume that you have selected input line 1 to accept the hardware trigger signal
and that you have set the Line Debouncer Time Abs parameter for input line 1 to 5 µs.
Basler ace GigE
Exposure Start Delay
21.48 µs
17.62 µs
48.97 µs
34.50 µs
45.54 µs
940 to 975 µs (with frame acquisitions overlapped)
940 µs (with frame acquisitions not overlapped)
Image Acquisition Control
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