Rockwell Automation 5370-CVIM2 Module - Manual (Page 99)

5 Chapter Chapter 4
Inspection Configuration
4–13
In the following example, the Overlap Acq/Insp parameter is set to 3, which
means that the CVIM2 system is configured to store up to three images
before the image processing for the previous image is completed. In this case,
if another trigger occurs before that completion, the system will issue a
trigger NAK.
Acq. 1
Trigger 1
Insp. Proc. 1
Acq. 2 Acq. 4 Acq. 3
Insp. Proc. 2 Insp. Proc. 3
Acq. 5
Trigger 2 Trigger 3 Trigger 4 Trigger 5 Trigger 6 = NAK
Overlap example with Overlap Acq/Insp parameter set to 3
In the example, a series of six triggers occurs. The interval between these
triggers is as short as possible consistent with completing each image
acquisition.
The sequence of events is as follows:
•
Trigger 1 occurs and starts the image 1 acquisition.
•
When image 1 has been acquired, processing begins on image 1. This
releases the storage resource used by image 1 and makes it available for
another image acquisition (image 2). At the same time, trigger 2 occurs to
start the image 2 acquisition.
•
Before image 1 has been processed, two more images will have been
acquired and stored (images 2 and 3), and another image acquisition will
have begun (image 4).
•
Midway through the image 4 acquisition, processing for image 1 ends and
processing for image 2 begins. This releases the storage resource used by
image 2 and makes it available for another image acquisition (image 5).
•
Before image 2 processing is complete, three images will have been
acquired and stored (images 3, 4, and 5). This is the maximum that is
allowed by the
Overlap Acq/Insp parameter (3) in this example.
•
Also before the second image processing is complete, trigger 6 occurs.
Since three images are already stored, and the system cannot store a
fourth image (in this example), it issues a Trigger NAK signal in response
to trigger 6.
NOTE: The maximum setting for the Overlap Acq/Insp parameter is 20;
however, because of the limitations of the image memory buffers, the
maximum setting in a particular application depends on whether the system
can be placed online. If the system will not go online with the current setting,
that setting may have to be reduced, or other adjustments may need to be
made, to enable the system to go online.