GS1-128 barcode

GS1-128 is a special variant of Code 128 that conforms to GS1 specifications. Unlike standard Code 128, GS1-128 automatically inserts a Function Code 1 (FNC1) character after the start character. The FNC1 character allows you to insert application identifiers into the symbol to encode data such as "best before" dates, batch numbers, quantities, or weights.

GS1-128 inherits the specifications for density, symbology structure, start and stop characters, and check digits from Code 128.

The Character Set

Like Code 128, GS1-128 supports the full ASCII character set, though it does not encode spaces. Although GS1-128 can encode all 128 lower ASCII characters, the character set itself contains only 102 characters. This is possible because Code 128 actually contains three different sets of 102 characters. The default character set in use for any GS1-128 barcode is determined by the start character. However, once a GS1-128 barcode is started, it is possible to switch between the different character sets in the middle of the barcode. Because it is possible to use any combination of the three character sets in a single barcode, GS1-128 gives you the greatest possible character density when encoding data into barcode.

The three character code sets can be summarized as follows:

  • Code A: The Full ASCII set, except for the 26 lower case letters.
  • Code B: The Full ASCII set, except for the 26 controlcharacters.
  • Code C: Double-density numeric. This character set is numeric-only, but any one character actually represents twodigits. Therefore, 100 of the 102 characters in code set C are used to represent the 100 two-character combinations from 00 through 99.

Special Characters

When creating a GS1-128 barcode, there are special characters that may be entered by typing in a combination of the caret (^) symbol and another character anywhere in your data stream. These combinations are listed below.

All Modes:

  • ^1 will insert a function 1 (FNC1) character. In GS1-128, FNC1 is the first symbol following the start character.
  • ^2 will insert a function 2 (FNC2) character.
  • ^3 will insert a function 3 (FNC3) character.
  • ^4 will insert a function 4 (FNC4) character.
  • ^% will insert a mod 10 check digit.

Manual Mode Only:

  • ^A will set the following data segment to Code A.
  • ^B will set the following data segment to Code B.
  • ^C will set the following data segment to Code C.
  • ^S will insert a Shift character.

Application Identifiers

Every GS1 symbol contains one or more application identifiers in addition to the data it encodes. An application identifier is a sequence of characters that relates a data string to a physical or logical thing, such as an item number, serial number, or due date.

Each application identifier tells the user what type of data follows; additionally, each one defines the length and data format of that same data string. Some application identifiers specify data fields containing a fixed number of characters, while others specify a variable length data field.

When customizing barcodes, use the GS1 Application Identifier Data Source Wizard to walk you through the process of adding application identifiers to your barcode and formatting the required data input for each one.

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