Msi Code (Variant Of Plessey); Plessey - Intermec 700 Series User Manual

APPENDIX C
S 2 of 5 (Standard 2 of 5)
The code S 2 of 5 (Standard 2 of 5 Code) is designed primarily for:
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The code S 2 of 5 is simple and straightforward. All information is contained in
the widths of the bars, with the spaces serving only to separate the individual
bars.
Bars can either be wide or narrow, and the wide bars are usually three times the
widths of the narrow bars. Spaces may be any reasonable width but are typical-
ly equal to the narrow bars. Narrow bars are identified as zero bits and wide
bars as one bits.
Remember the code structure by associating the bar positions from left to right
with weighting factors 1, 2, 4, 7, and parity. Exceptions to this rule are zero,
start, and stop. This code is a discrete code, since the white spaces between the
characters are not part of the code. Because the white spaces carry no informa-
tion, their dimensions are not critical.
The S 2 of 5 code is self-checking, meaning a scanner passing through a printing
void would detect the proper ratio of wide bars to total bars. When the scanner
spots an error, a non-read will occur.

Plessey

Plessey finds its origin in the pulse width modulated (PWM) code developed in
England. It is widely used for shelf markings in grocery stores. Pulse width
modulated codes represent each bit of information by a bar and space pair. A
zero bit consists of a narrow bar followed by a wide space, while a one bit con-
sists of a wide bar followed by a narrow space. It is mainly a numeric symbology
(0–9) with six extra characters available for assigning any symbol or letter de-
sired.
Plessey codes are not self-checking and employ a variety of check characters.
Plessey employs a polynomial-based Cyclic Redundancy Check (CRC). For start
and stop characters, Plessey employs a 1101 and previously used a 0101.
This symbology is very limited about what information can be encoded. It is not
considered for new applications.

MSI Code (Variant of Plessey)

In addition to Plessey characteristics, the MSI Code employs a Modulus 10
Check. For start and stop checks, MSI employs a single bit pair of 1 as a start
symbol and a single bit pair of 0 as a stop symbol. MSI reverses the 1-2-4-8 BCD
pattern for bit pair weighting to 8-6-2-1.
Warehouse inventory handling
Identification of photo finishing envelopes
Airline tickets
Baggage and cargo handling
700 Series Color Mobile Computer User's Manual
Bar Codes
C-7