Plessey Code

Plessey Code is a 1D linear barcode symbology based on pulse-width modulation, developed in 1971 by The Plessey Company plc, a British-based company.

[1] It is one of the first barcode symbology, and is still used rarely in some libraries and for shelf tags in retail stores, in part as a solution to their internal requirement for stock control.

The chief advantages are the relative ease of printing using the dot-matrix printers popular at the time of the code's introduction, and its somewhat higher density than the more common 2 of 5 and 3 of 9 codes.

It has later led several variations as Anker Code by ADS Company, Telxon, and MSI (also known as Plessey modified).

It is difficult to have the specifications for them nowadays and thus hard to tell the differences between them (except for MSI), because it was mainly available as a paper document and has since been discontinued.

A "0" bit is represented as a narrow bar, followed by a wide space.

The barcode comprises: The forward start code is "1101".

The character of the text to encode are hexadecimal values encoded as reversed BCD The check code for error detection and correction is as CRC, using polynomial division.

, with c > 0.127 mm Bit dimension in mm : Values are slightly different for Anker Code Before and after each barcode, there should be margins of 4 bits.