MSI Plessey is numeric and variable length linear barcode symbology that developed by the Plessey Company of England. It is mainly used in retail business. Each character consists of eight elements, four bars and four spaces. The character set includes the digits 0 through 9. A Modulo 10 checksum is appended to the end of the code.
MSI Plessey is the most common bar code that is used for inventory tracking on the shelves in supermarkets. While MSI Plessey is not actually used on the products themselves (which contain UPC codes), it is used on the front edge of the shelves to indicate where each product is stored. The MSI Plessey barcode is the variants of the Plessey barcode. It is a pulse-width modulated non-self checking code and primarily used in store shelf labeling.
Most of the applications support MSI only for backward compatibility, because MSI/Plessey is based on Pulse-Width Modulation technology. MSI Plessey requires start/stop characters. MSI is used to encode numeric data and check digit is required to add at the end of the data.
The MSI Plessey Code is pulse width modulated and non-self checking code. Each character is represented by 4 bars; a narrow bar represents binary 0 and wide bar represents binary 1. The bars have the binary weights 8-4-2-1. It is possible to encode the digits 0 through 9 and the letters A through F, although this barcode is most often used just for numeric information. The start character is single wide bar and the stop character is two narrow bars.
Structure of a MSI/Plessey barcode:
A typical MSI/Plessey barcode has the following structure: