Service manual

A.8b Bar Code Basics
A bar code is a group of rectangular bars and spaces arranged in a preset
pattern. The pattern is organized to represent elements of data referred to
as characters. The standard industry codes can represent several
alphanumeric characters.
There are many different types of bar codes. Each type uses its own
symbology, which defines how the bars and spaces represent the letters and
numbers.
The figure below shows each part of a bar code. The labels for each part
remain the same even if the position, orientation, or type of bar code
changes.
The GBR 420T with the Accu-Sort Model 30 uses the 3 of 9 code or Code
39 - fixed or variable length. This was the first code developed that used
both numbers and upper-case letters. It is the most recognized and widely
used for non-retail applications. Each character is represented by a
stand-alone group of 5 bars and 4 spaces. The basic code set includes 0-9,
A-Z, * which is used for the start and stop characters, and six other symbols
- . $ / + and % for a total of 43 characters. Because each of the characters
are discrete and self-checking, Code 39 provides a high level of data
security. The Model 30 automatically checks all data for this symbology.
The bar code width must not be printed smaller than 0.010" (.025 mm).
Recommended width is 0.015", code height is 3/8 inch. Minimum quiet zone
start and end of .25 inches.
Bar coding, sizing, tolerance ratio tolerance per ANSI MH10.8-1983. Print
quality must meet or exceed ANSI Grade B per ANSI X3.182, BAR CODE
PRINT QUALITY GUIDELINE.
A.8c Adjusting Your Model F30 Scanner
Your scanner can be mounted in any direction depending on the scheme of
your bar codes. Ladder orientation refers to a bar code whose bars look
like a ladder when facing the bar code’s direction of travel. Picket Fence
appear as a picket fence when facing the direction of travel. Regardless of
the direction of travel, the scan line must be perpendicular to the bars.
In some applications, codes are printed on glossy paper or covered with a
shiny material such as cellophane. When this happens, it is possible that
the code surface reflects so much laser light that it is very difficult for the
scan head to decode the bar code.
To avoid reflections from the surface of glossy bar codes do not mount the
scan head parallel with the object to be scanned. Mount the scan head at a
five to ten degree angle so the laser beam reaches the bar code at a slight
angle.
INTRODUCTION
420T V6LT OPERATOR & SERVICE MANUAL ISSUE 2009/06 Rev. 6/21/2011 SECTION A – PAGE 53
071-33370-400
Bar Code Example