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Plessey Barcodes
Plessey barcodes, also known as Plessey Code or Plessey Pattern, are a type of linear barcode symbology that encode data using a series of varying width bars and spaces. Developed in the 1970s by the Plessey Company in the United Kingdom, Plessey barcodes were initially used for retail price marking and inventory control. While not as widely used as some other barcode types today, Plessey barcodes remain relevant in certain niche applications, particularly in areas where legacy systems are still in use or where compatibility with older technology is required.
One of the distinguishing features of Plessey barcodes is their simplicity and ease of decoding. Plessey barcodes consist of alternating black and white bars of varying widths, with each combination representing a specific numeric or alphanumeric character. Despite their simplicity, Plessey barcodes can encode a limited amount of data, typically comprising numeric digits or a small set of alphanumeric characters. This makes them suitable for applications where only basic identification or tracking information is required, such as library books or asset tagging.
However, with the advent of more advanced barcode symbologies capable of encoding larger amounts of data, Plessey barcodes have seen a decline in usage in favor of more versatile options. Nonetheless, they still find occasional use in specific industries or applications where compatibility with existing systems is necessary. Overall, while Plessey barcodes may not be as prevalent as they once were, their legacy lives on in certain niche markets and serves as a reminder of the early days of barcode technology.
Another variation is known as the MSI Code.
Plessey offers a full range of HEX digits 0-F. The bit pattern of the bits sets the high order bit at the right which is reverse of how we normally think of bits these days. (MSI puts the high order bit on the left).
The start bar is always "D" (1101) and the terminator can be two binary 1's (11) if the barcode is to be read from left to right only. If the barcode can be read in either direction the terminator will be a single binary 1 (1) and is followed by a reverse of the start character or the "B" (1011).
| Digit | Strip Bits | Binary Value |
| 0 | 100100100100 | 0000 |
| 1 | 110100100100 | 1000 |
| 2 | 100110100100 | 0100 |
| 3 | 110110100100 | 1100 |
| 4 | 100100110100 | 0010 |
| 5 | 110100110100 | 1010 |
| 6 | 100110110100 | 0110 |
| 7 | 110110110100 | 1110 |
| 8 | 100100100110 | 0001 |
| 9 | 110100100110 | 1001 |
| A | 100110100110 | 0101 |
| B | 110110100110 | 1101 |
| C | 100100110110 | 0011 |
| D | 110100110110 | 1011 |
| E | 100110110110 | 0111 |
| F | 110110110110 | 1111 |
| START | 110110100110 | 1101 |
| STOP > | 110110 | 11 |
| STOP < > | 110110100110110 | 11011 |
You can use the stripe bits can be used to generate the graphic pattern. If you want to see this trick, check out the MSI Code page. Plessey uses a cyclic (or polynomial) check code technique which is applied to the reading of barcode labels and transmission of data. This technique is a fair compromise between the extra redundancy and the error detecting power. Roughly one undetected error per hundred million 6 digit transactions.
If you would like to generate your own Plessey Barcode, please visit our free barcode generator page. Make your code, save it and use it how ever you like.