Allen-Bradley 2755-HDG-4 User Manual page 106

G–6
S
Scanner
An electronic device used to scan bar code symbols and produce a
digitized pattern that corresponds to the bars and spaces of the symbol.
Its three main components are:
1. Light source (laser or photoelectric cell) - illuminates a bar code.
2. Photodetector - registers the difference in reflected light (more
light reflected from spaces).
3. Signal conditioning circuit - transforms optical detector output
into a digitized bar pattern.
Scanning Mode
The scanner is energized, programmed, and ready to read a bar code.
Scanning Sequence
A method of programming or configuring parameters for a bar code
reading system by scanning bar code menus.
Self Checking Code
A symbology that uses a checking algorithm to detect encoding errors
within the characters of a bar code symbol.
Start / Stop Character
A pattern of bars and spaces that provides the scanner with start and stop
reading instructions and scanning direction. The start and stop characters
are normally to the left and right margins of a horizontal code.
Symbol
A scannable unit that encodes data within the conventions of a certain
symbology, usually including start/stop characters, quiet zones, data
characters, and check characters.
Symbology
The structural rules and conventions for representing data within a
particular bar code type (e.g. UPC/EAN, Code 39).
Publication 2755-6.2