16
16
3.3.4.2 Pulse-width Exposure Control
This is selected as Async Pulse-width Control in trigger mode (00 23, 00 00 00 02). The pulse width
between the falling (leading) edge and the rising (trailing) edge is the exact period of the exposure.
The pulse width is not synchronized with the internal timing such as horizontal clock but only latched
with the high speed pixel clock in 25 ns of latency to reproduce identical timing as the trigger pulse.
This is also useful tool for synchronizing multiple cameras triggered with a variable exposure.
3.3.4.3 Internal Exposure Control Pulse Generator
The Coyote software allows user to trigger GigE cameras from the PC or host. See PLC functions in
section 4.6.1.
Note: Some early models may be required firmware upgrade to implement this function.
3.3.5 Full Scan and Partial Scan (00 23, 00 00 00 10, -11, -12, -14)
3.3.5.1 Full Scan: (00 00 00 00, -01, -02, -03, -04)
The basic platform of
GP-series
use the progressive scan CCD (or CMOS). The full scan image is by
progressive scan, which does not reduce the resolution by capturing one frame (i.e. field image in
Interlace reduces the resolution). The platform uses 40MHz clock as standard and the typical full frame
rate is 100 fps for VGA, 31 fps for XGA, and 23 fps for SXGA. The Coyote grabber function “image
size” is set to cover the camera’s active pixel data. The horizontal number is multiple of 4 and the verti-
cal is the exact vertical pixel numbers. In our VGA camera, CCD output of horizontal pixel data is 659
x 494 but the best number of 4’s multiple is 656. Therefore, the data sheet shows active pixels of 656 x
494 as the GigE camera data.
3.3.5.2 Partial Scan: (00 00 00 10, - 11, -12, -14)
The
GP-series
output the full frame images in higher frame rate than most of similar cameras but also
output the partial scan images with even higher frame rate. The VGA full scan is 100 fps but 240 line
partial scan outputs 190 fps. The factory set partial scan lines are 240 for the VGA, 400 for the XGA,
720 for the SXGA. The location of starting lines is programmable (00 26). The vertical area is variable
only in horizontal line counts (Horizontal pixel number does not change). This field of view adjustment
is helpful to align the point of interest without moving the camera position.
The exposure control and other functions of normal scan are also applied to the partial scan modes.
3.3.5.3 ROI Setting in Frame Grabber Function (Coyote Application)
Along with the camera side of partial scan, the frame grabber function of the GigE cameras can select
specific size of ROI (Region of Interest). This does not help increasing the fame rate but the data
transmission and bandwidth can be improved by sending small section only, which, in turn, speeds up
the signal processing. See the image size setting in Coyote Application 4.4.2.
3.3.6 Strobe/ Internal Exposure Signal Output
For all async reset modes, the internal exposure pulse is output from the GPIO pin (Pin #3). This can
be used to trigger strobe or other control devices. The output is TTL - active high.
The signal is same as the internal exposure control pulse so that it can be monitored for the exposure
timing, image grabbing, and internal frame rate in each mode. The internal delay of all resets is 4 pixel
clock.
(Fig. 20 and
21)
GEViCAM Inc
PW control
Strobe out and
trigger
Fig. 20 Async Trigger and Internal Reset Timings
Fig. 21 Internal Reset Delay
Содержание GP-151400
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