About MSI Plessey Barcodes
MSI Plessey (also known as Modified Plessey) is a numeric 1D linear barcode symbology developed by MSI Data Corporation, based on the original Plessey barcode. It is a continuous symbology designed for inventory shelf labeling and product tracking. Unlike discrete barcodes, MSI Plessey represents digits using specific bar patterns where the spaces carry information. It is heavily used in retail warehousing and grocery logistics for internal tracking and auditing.
How MSI Plessey Encoding Works
MSI Plessey encodes numeric digits (0-9) using a binary system where each character consists of four bits (bars and spaces). It requires a start code, the data digits, one or two check digits, and a stop code. The check digits are calculated using a Modulo 10 or Modulo 11 algorithm (or a combination of both). The double-modulo check option provides an extremely high level of protection against scanning errors, which is critical for inventory databases.
Common Applications and Industries
MSI Plessey is used primarily in retail and supermarket environments for shelf labeling, price auditing, and stock replenishment. Store employees use handheld scanners to scan MSI barcodes on shelf edges to check current stock levels, verify prices, and print reorder tickets. It is also used in warehouse storage bins, library book tracking, and document archiving.
Advantages & Limitations
MSI Plessey is highly optimized for numeric inventory lists, offering reliable performance on shelf labels. The multiple check digit options (Mod 10/11) ensure high data security. The main limitation is its lack of support for letters and special characters, restricting its use to purely numeric databases. It is also less compact than modern options like Code 128 or GS1 DataBar.