An Introduction To Barcodes
am 05.01.2008 12:13:43 von 88059355Barcodes encode numeric or textual information in a printable, machine-
readable form. The use of barcodes can significantly reduce cost of
warehouse management and inventory. Two main forms of barcodes exist
today: Linear or normal barcodes encode data over a horizontal stretch
of space or one dimension. This kind of barcode typically encodes
between four and forty digits or characters. So called area codes
encode data in two dimensions, resulting in much higher density which
allows for up to three thousand characters to be encoded.
Most linear barcode types will only encode numbers or digits. Two
notable exceptions are Code 39 and Code 128 which can also encode
alphanumeric characters like letters. Two dimensional area codes
usually encode numbers, letters and special characters.
The most common linear barcode type is Code EAN which is used to
encode article numbers in retail. It's used throughout the world with
the notable exception of the USA which uses a related code, Code UPC,
for the same purpose. A special form of Code EAN carries a so called
Addon, a smaller barcode next to the main barcode that can encode
pricing information and the like. Code EAN with a five digit Addon is
used to encode ISBN (International Standard Book Number), while Code
EAN with a two digit Addon is used to encode ISSN (International
Standard Serials Number).
Other notable linear barcode symbologies and their applications
include Code 39 (used for pharmaceuticals), Code 128 (warehouse
management and retail) and Code Two-Of-Five (warehouse management and
inventory).
The most common two dimensional area codes are PDF417 and Datamatrix,
both of which are used in manufacturing, package tracking and similar
applications which require large data amounts to be encoded.
Barcode Checksums
To ensure safe and error free reading and scanning of barcodes, all
common barcode symbologies support so called checksum or check digit
schemes. A checksum or check digit is an additional character or
number that is calculated from the encoded data and appended to the
barcode. While reading the barcode the scanner or reader can verify
the checksum and determine if the barcode was scanned correctly. This
is especially important if the barcode can easily be damaged or be
tampered with. Simple check digit systems like the sort that is used
with most linear barcodes will only detect simple errors, like a
missing character. More sophisticated systems, especially those used
with area barcodes can not only detect but also repair any damage that
may have occurred to the code.
Barcode Applications
Today barcodes enjoy wide spread use through all types of businesses.
The first major application of barcodes was in the retail sector where
the codes would encode article numbers, manufacturer data and pricing.
Another prominent use of barcodes is in the transport industry where
the codes carry address and tracking information. Finally, two
dimensional area codes have recently gained much popularity for use in
personal identity cards, drivers licenses and so forth. They are also
used for the tagging of electronic parts like computer or memory
chips.
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