Basler ace acA1920-155, User Manual, Page: 132 / 326

Image Acquisition Control AW00123404000
122 Basler ace USB 3.0
Trigger Width Exposure Mode (acA2000-165 and acA2040-90)
Trigger width exposure is especially useful if you intend to vary the length of the exposure time for
each captured frame.
When trigger width exposure mode is selected, the exposure time for each frame acquisition will be
the sum of two individual time periods (see
Figure 54 ):

The first time period is the exposure time that is controlled by the ExFSTrig signal: If the
camera is set for rising edge triggering, the first time period - and therewith the exposure time -
begins when the ExFSTrig signal rises. The first time period ends when the ExFSTrig signal
falls.
If the camera is set for falling edge triggering, the first time period begins when the ExFSTrig
signal falls. The first time period ends when the ExFSTrig signal rises.

The second time period is the exposure time offset, C
4
. It is automatically added to the first
time period by the camera’s sensor. The length of the exposure time offset depends on the bit
depth of the current pixel format (8 bit or 12 bit) and on the currently available USB 3.0
bandwidth (expressed as "Device Link Throughput").
The exposure time offsets, C
4
, and their dependence from pixel format bit depth and USB 3.0
bandwidth are given in Table 22 and Figure 55 .
Fig. 54: Trigger Width Exposure with Adjusted Rising Edge Triggering; (Exposure Start Delays Is Omitted)
Note that C
4
is identical to the camera’s minimum allowed exposure time. For the camera’s
minimum allowed exposure times, see Table 23 on page 127 .
ExFSTrig Signal Period
Timing-adjusted
ExFSTrig Signal
Exposure (Total; Wanted)
Exposure, Controlled
by Timing-adjusted
ExFSTrig Signal
Exposure, from
Exposure Time Offset; C
4
Timing Adjustment