permanence: once the product code is assigned, it will not be changed, and it is lifelong. When this product is no longer produced, its corresponding product code can only be shelved and cannot be reused and redistributed to other commodities.
meaningless: in order to ensure that the code has enough capacity to meet the needs of frequent product updates, it is best to use meaningless sequence codes.
code system difference of bar code
UPC: (Uniform Product Code)
It can only mean that the number
has four versions: A, B, C, D and E.
Version A-12 digits
Version E-7 digits
The last digit is a parity bit
The size is 1.5 "wide. Used in industry, medicine, warehouse and other departments
When UPC is decoded as twelve bits, The definition is as follows:
the first digit = digital identification (established by UCC (Uniform Code Committee)).
the 2nd-6th digits = identification number of the manufacturer (including the first digit)
the 7th-11th digits = unique manufacturer product code
the 12th digit = used for error detection.
Code 3 of 9 :
can represent letters, numbers and other symbols ***43 characters: A -Z,-9,-.$/+%, Pace
The length of bar code can be changed
The * sign is usually used as the starting and ending symbol
The check code is not used
The code density is 3-9.4 characters/inch
The blank area is 1 times that of the narrow bar
It is used in industry, books and ticket automation management
Code 128:
. String
String variable length
Symbol contains check code
There are three different versions: A, B, and C
128 characters can be used in A, B, In the three character string sets of or C,
used in industry, warehouse and retail wholesale
Interleaved 2-of-5 (I2 of 5):
can only represent serial bar codes with numbers -9
variable length
, all bars and spaces represent codes, and the first number starts with a bar. The second number is composed of blanks
The blank area is 1 times wider than the narrow bar
It is applied to commodity wholesale, warehouse, airport, production/packaging identification and industry
Barcode has high recognition rate and can be applied to fixed barcode scanner reliable scanning
It has the highest density among all one-dimensional barcodes
Codabar:
It can represent the number . The characters $,+,-,and four characters A, B, and C D, which can only be used as start/stop symbols, are
variable length
no check bit
used in material management, libraries, blood stations and current airport parcel delivery
the blank area is 1 times wider than the narrow strip
discontinuous bar code. Each character is represented as four blank
PDF417 (two-dimensional bar code):
A bar code composed of multiple lines
can store a large amount of data without connecting to a database
It can be used in: hospitals, driver's licenses, material management and cargo transportation
When the bar code is damaged to some extent, error correction can make the bar code correctly decoded
PDF417. It is a multi-line, continuous, variable-length symbol with a large amount of data. Each bar code has 3-9 lines, and each line has a beginning part, a data part and an end part. Its character set includes all 128 characters, and the maximum data content is 185 characters.