An introduction to bar codes
by: Humphrey Appleby
Barcodes encode digital information in a text or print version, machine readable. The use of bar codes can significantly reduce costs in warehouse management and inventory. Two main types of bar codes exist today: linear or normal barcodes encode data on a horizontal distance of space or a single dimension. This type of bar code encodes usually between four and forty digits or characters. The so-called area codes encode data in two dimensions, resulting in much higher density that allows a maximum of three thousand characters to encode.
Most types of linear bar codes encode only numbers or figures. Two notable exceptions are the Code 39 and Code 128, which can also encode alphanumeric characters as letters. Two-dimensional area codes typically encode numbers, letters and special characters.
The type of linear bar code is the most common UPC code that is used to encode the article numbers in detail. It is used worldwide with the notable exception of the United States that uses a code attached, UPC, in the same purpose. A particular form of EAN involves a so-called Addon, a small bar code barcode next to the main can encode price information and more. EAN Addon with a five-digit code is used for ISBN (International Standard Book Number), while the bar code with a two digit addon is used to encode ISSN (International Standard Serials Number).
Other symbologies linear bar codes and their applications including the code 39 (used in pharmaceuticals), Code 128 (warehouse management and retail) and two code-of-five (warehouse management and inventory ).
The two most common area codes dimensional PDF417 and Datamatrix, which are both used in the manufacture, package tracking and similar applications that require large amounts of data to be encoded.
Barcode Checksums
To ensure the security and error-free reading and scanning bar codes, all bar code symbologies support so-called common control or check digit schemes. A checksum or check digit is a character more or number that is calculated from the data encoded and appended to the barcode. While reading the bar code on the scanner or reader can verify the checksum and determine if the barcode was scanned correctly. This is particularly important if the bar code can be easily damaged or altered. Simple control systems data, like the type that is used with most linear barcodes only detect simple mistakes like a missing person. More sophisticated systems, particularly those used with bar code field can not only detect but also repair damage that might occur in code.
Barcode Applications
barcodes now enjoy widespread use across all types of businesses. The first major application of bar codes has been in the retail sector where the codes do not encode article numbers, manufacturer data and pricing. Another important use of barcodes is in the transport sector where the codes address the conduct and monitoring information. Finally, two area dimensions have recently gained much popularity for use in personal identity cards, driving licenses, etc.. They are also used for marking electronic components such as computers or memory chips.
FOLD.COM article - The Authority of barcodes.
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FOLD.COM article - The Authority of barcodes.