Rockwell-automation 2755 AtomScan Bar Code Reader Manual de usuario descargar pdf (Pagina 25)

3–5Designing Your Scanner System

Publication 2755-6.9

When to Use a Raster Reader

Single line readers should always used in step ladder orientation.

Raster readers are beneficial in picket fence applications with

symbols printed by a dot matrix printer, where the bars have ragged

edges or voids, or where the spaces have specks in them.

The AtomScan

reader might read a symbol correctly even if the

symbol or package is not correctly oriented. Refer to the figure

below for various package orientations. Tilt, pitch, and skew can

affect the reader’s ability to read bar code symbols.

Reader

Correctly Positioned

Symbol and Package

Tilted Symbol

Pitched Package

and Symbol

Skewed Package

and Symbol

Tilt

A symbol is tilted when the symbol’s bars are not 90° to the scan

line. The symbol can be read with any tilt, provided the scan line

passes through all bars and quiet zones on each sweep for the

required minimum number of scans. Tilt may reduce the number of

scans in a given application.

Pitch

A symbol is pitched when the symbol’s bars are at different distances

from the reader. From the reader’s perspective, a pitched symbol

appears to have a smaller narrow element width than it actually has.

This may reduce both the read rate and the read range. However, the

symbol can still be read if the apparent narrow element width is

within the reader’s specifications.

Note: Like skew, pitch may be used deliberately to reduce specular

reflection, as long as the application still has the number of scans per

symbol it needs.

Tilt, Pitch, and Skew

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Rockwell-automation 2755 AtomScan Bar Code Reader Manual de usuario Pagina 25