Rockwell Automation 5370-CVIM2 Module - Manual (Page 411)

5 Chapter Chapter 7
Inspection Tools
7–173
Figure 7.139 illustrates the Min+%Diff High threshold mode, using the
default values for the “ % ” and “ Limit ” settings.
Figure 7.139 Example: “Min+%Diff High” Threshold Mode
Minimum gray
scale value = 115
Minimum gray
scale value = 249
Threshold at
50% level (182)
High limit = 255
In this example, the profile tool finds the minimum gray scale value at 115
and the maximum value at 249. It calculates the difference, then places the
threshold at the minimum plus % difference, or 115 + (50% x (249 – 115),
which is 182.
Min+%Diff Low Mode
When you pick Min+%Diff Low in the Thresh Mode panel, the Threshold
panel appears as shown in Figure 7.140 (page 7–174).
In this mode, the slide bar has two cursors (the % and Low cursors) and two
corresponding fields (the % and Limit fields). The default value for the “ % ”
field is 50, and the default value for the “ Limit ” field is 128.
The Min+%Diff Low threshold mode enables you to set up a dynamic
threshold, along with a minimum limit below which the threshold may not go
during run mode operation.
The concept of the Min+%Diff Low threshold mode is identical to the
concept of the Min+%Diff High threshold mode, except that the threshold
has a low limit instead of a high limit.