Basler ace acA1920-155, User Manual, Page: 172 / 326

Image Acquisition Control AW00123404000
162 Basler ace USB 3.0
6.9 Acquisition Timing Chart
Figure 76 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 76 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 and makes them available for transmission as
called by the host PC.
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 exposure start delay varies from camera model to camera model. The table below shows the
exposure start delay for each camera model (see Table 31 on
page 163 ).
The sensor readout time is the amount of time it takes to read out the data for an acquired frame
from the imaging sensor.
The frame transmission time is the amount of time it takes to transmit an acquired frame from the
camera to the host PC via the bus.
The frame transmission time can vary between frames and partly depends on when the host PC
calls for data transmission.
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 transmission start delay can vary between frames and largely depends on when the host PC
starts calling for data transmission.
Note that a propagation delay of unspecified duration precedes the exposure start delay when
applying an ExFSTrig signal. For more information about propagation delays, see Section 5.10 on
page 69 .