Rockwell Automation 5370-CVIM2 Module - Manual (Page 62)

5 Chapter Chapter 3
Image Acquisition Parameters
3–23
Figure 3.15 Example: Offset Selection
Feature A
Offset 1.0
Feature B
Offset 1.0
Units Selection
Selecting the “world units” involves simply selecting the appropriate name,
such as “
Inches ,” for the calibrated measurements. When you pick the Units
field, a “typewriter keyboard” appears on the display. Initially, the name
“
Pixels ” appears in the Units field and in the keyboard name field. To select
a different world units name, pick the characters of that name, then pick the
button on the keyboard.
NOTE: The choice of world units name has no effect on the scale
computations. It is for display purposes only.
Performing Scale Computation (Computed Mode Only)
The scale computation is performed in two steps: determining (“learning”)
the distance between the two offsets on the calibration gage in pixels, and
entering the distance between those offsets in “world units,” such as inches.
The calibration object shown in Figure 3.14 (page 3–22) and Figure 3.15
provides an example for illustrating a scale computation. When you pick the
Nominal field (which initially is always 1.000), the gage performs the learn
operation, as shown in Figure 3.16 (page 3–24). The gage measures the
distance between the Feature A and Feature B offsets along the X calibration
gage and displays the result, in pixels, in the
Nominal field.