Code 128

Code 128

• Code 128 is a very high-density barcode symbology. It is used for alphanumeric or numeric only barcodes.
• It can encode all 128 characters of ASCII and, by use of an extension characater(FNC4), the Latin-1 characters defined in ISO/IEC 8859.

Specificaion
A code 128 barcode will have six sections.
1. Quiet zone.
2. Start character.
3. Encoded data.
4. Check character.
5. Stop character.
5. Quiet zone.

Subtypes

• Code 128 includes 108 symbols
1. 103 data symbols.
2. 3 start symbols.
3. 2 stop symbols.

• The symbols consists of 3 blacks and 3 white spaces of varying widths.
• Each bar width is 1 to 4 modules(a module is a unit width) wide.
• But the stop symbols are fixed width: the sum of widths of the 3 black bars and 3 white bars is fixed.
• The stop pattern is composed of two overlapped symbols and has four bars.
• The stop pattern permits bidirectional scanning.
• The stop pattern if reads from left to right then stop symbol is recognized.
• If stop pattern reads from right to left then reverse stop symbol is recognized.
• A scanner seeing the reverse stop symbol then knows it must read the symbol in reverse.

Notes