Rockwell Automation 5370-CVIM2 Module User Manual

Page 77

Chapter 3

Image Acquisition Parameters

3–38

The effect of adjusting the

Vertical Timing

parameters is described as

follows:

Acq.Start (1/2 Lines) –– This parameter indicates the point at which the
image acquisition begins for the purpose of image processing and display.
Normally, the default setting of 40 is appropriate; however, the

Acq.Start

(1/2 Lines)

value can be set within the following range:

Value

40 + (480

Acq. Lines)

Acq.Lines (1/2 Lines) –– This parameter indicates the number of half–lines
of the image field that are acquired, beginning at the starting point set by the

Acq.Start (1/2 Lines)

parameter. Normally the default value of 480 is

appropriate; however, the

Acq.Lines (1/2 Lines)

value can be set within the

following range:

Value

520

Acq. Start

Figure 3.28 (page 3–39) illustrates three image displays in which the

Acq.Lines (1/2 Lines)

values are set to 480 (default), 240 and 64.

As the examples in Figure 3.28 show, the effect of decreasing the value of
the

Acq.Lines (1/2 Lines)

parameter is to reduce the number of half–lines

acquired, and the result is to decrease the image height.

Changing both of these parameters might be useful in a situation in which a
narrow, horizontally oriented inspected object lies in a narrow band at the
center (or lower) part of the image. In this case, you could set the

Acq.Start

(1/2 Lines)

parameter to, for example, 220, and set the

Acq.Lines (1/2

Lines)

parameter to 64. The result would be a vertically narrow image with

just enough room to contain the inspected object.

Figure 3.29 (page 3–40) illustrates the result, using a pen as the inspected
object. In this example, the pen was located in a lower part of the unmodified
full image, whereas the vertically truncated image containing the pen appears
“justified” at the top of the image display.

In all cases the sum of the

Acq.Start (1/2 Lines)

setting and the

Acq.Lines

(1/2 Lines)

setting cannot exceed 523. Any combination of the two

parameters is acceptable whose sum does not exceed 523.