MSI Plessey, also called MSI or Modified Plessey, is a numeric-only 1D barcode used on warehouse shelves, bins and storage containers. barKoder reads MSI barcodes, with the check digit scheme you choose, using the phone and tablet cameras in your iOS, Android and web apps.
| Type | Continuous, non-self-checking linear (1D) symbology. Each digit is 4 bits, and each bit is a bar and a space, so a digit has 8 elements. |
| Character set | Digits 0-9 only |
| Capacity | Variable length, set by the application |
| Check digit | One or two check digits: mod 10 (the most common), mod 11, mod 1010 or mod 1110 |
| Standard | Specification from MSI Data Corporation, based on the original Plessey Code |
| Typical uses | Warehouse shelf and bin labels, storage containers, inventory control |
Modified Plessey, usually shortened to MSI, was developed by the MSI Data Corporation from the original Plessey Code. It encodes digits only, which makes it a fit for shelf locations, bin numbers and item numbers in inventory control.
Each digit is written as 4 binary bits. Each bit is a bar followed by a space: a narrow bar and wide space for 0, a wide bar and narrow space for 1. A symbol has five parts:
MSI is not self-checking: a misread bar can turn one digit into another. The check digit is what catches the error, so the reader has to know which scheme the label uses.
The symbology allows several check digit schemes, and the label printer decides which one is used. Set barKoder to the same scheme so it validates the result.
| Scheme | How it works | barKoder MSI checksum type |
|---|---|---|
| None | No check digit. The least common choice, and risky because MSI is not self-checking. | Disabled |
| Mod 10 | One check digit calculated with the Luhn algorithm. The most common scheme. | Mod10 |
| Mod 11 | One check digit from a weighted sum, modulo 11. IBM weights run 2 to 7; NCR weights run 2 to 9. | Mod11 (NCR weights), Mod11IBM (IBM weights) |
| Mod 1010 | Two check digits: a mod 10 digit, then a second mod 10 digit calculated over the data plus the first one | Mod1010 |
| Mod 1110 | Two check digits: a mod 11 digit first, then a mod 10 digit | Mod1110 (NCR weights), Mod1110IBM (IBM weights) |
MSI is a legacy code that stays in use where shelf and bin labels were printed years ago.
MSI is used mainly for inventory control: marking storage containers, shelves and bin locations in warehouses. Warehouse apps scan these labels to record where stock sits.
Barcode scanning for warehousing →MSI also appears on retail shelf labels used for inventory control. Staff apps that count stock read these labels alongside the EAN and UPC codes on the products.
Barcode scanning for retail →barKoder's barcode generator lists library systems among MSI's users, alongside warehousing. Libraries also use Codabar and Telepen, which barKoder reads too.
Barcode scanning for education →The barKoder Barcode Scanner SDK reads MSI Plessey on iOS, Android, the web, Windows and Linux, and in Flutter, React Native, .NET MAUI, Capacitor, Cordova and NativeScript apps. These features matter most for this code.
Set the check digit scheme your labels use: disabled, mod 10, mod 11, mod 1010, mod 1110, or the IBM variants of mod 11 and mod 1110. The setting is documented for the Web, Android, Flutter, React Native and other SDKs.
setMsiChecksumType in the API reference →Reads all supported 1D barcodes with strong deformation, such as labels on rounded containers or wrinkled tags, where no straight line crosses all the bars.
Segment Decoding →Decodes several barcodes in one camera view, whatever their type or size. The feature page names price tags and inventory counting as use cases.
Batch MultiScan →The free barKoder barcode generator creates MSI Plessey barcodes as PNG images. Print a few and scan them with the demo app before you test your real shelf labels.
Free barcode generator →Enable the MSI decoder and set the check digit scheme. The first line uses the decoder constant from the barKoder docs; the second is the docs' own MSI example.
Barkoder.setEnabledDecoders(Barkoder.constants.Decoders.Msi);
Barkoder.setMsiChecksumType(Barkoder.constants.MsiChecksumType.mod1010);Replace mod1010 with the scheme your labels use. On Android the decoder is Barkoder.DecoderType.Msi.
MSI checksum settings on other platforms: Android, Flutter and React Native API references.
Install the free barKoder demo app, or open the web demo, and scan your own MSI shelf and bin labels before you integrate the SDK. No labels at hand? Create MSI Plessey test codes with the free barcode generator.
iPhone and iPad
Scan with your camera, or point it at the QR code to open the App Store.
Android phones and tablets
Scan with your camera, or point it at the QR code to open Google Play.
Any modern browser
Runs the Web SDK in your browser, on desktop or mobile, with nothing to install.
Test with known samples. Print or display the testing sheet and scan each 1D and 2D barcode with the demo app. The data sheet summarizes the SDK for your team.
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MSI Plessey, also called MSI or Modified Plessey, is a numeric-only linear barcode developed by the MSI Data Corporation from the original Plessey Code. Each digit is encoded as 4 bits, and each bit as a bar and a space. It is used mainly for inventory control, on warehouse shelves, bins and storage containers.
It depends on who printed the label. Mod 10, based on the Luhn algorithm, is the most common. Mod 11 adds one check digit with weighted sums (IBM and NCR use different weights). Mod 1010 adds two mod 10 digits, and mod 1110 adds a mod 11 digit followed by a mod 10 digit. Some labels have no check digit. Look at a known label, or ask the system that prints them, and set the same scheme in barKoder with setMsiChecksumType.
Use the free barKoder barcode generator: pick MSI Plessey, enter your digits and download the barcode as a PNG image. MSI encodes digits only. Print the result or show it on screen and scan it with the demo app to check your setup.
The most common cause is a check digit mismatch. If the scanner expects mod 10 and the label was printed with mod 1010, mod 11 or no check digit, the read is rejected. Set the MSI checksum type to the scheme your labels use, or disable it while you find out. Also check that the MSI decoder is enabled in your scanner settings.
Yes, if the scanning library supports MSI. barKoder reads MSI Plessey with the camera on iOS and Android phones and tablets and in web browsers, and lets you set the check digit scheme. Try it with the free demo app or the web demo.
Test the SDK on your own shelf and bin labels with a free 30-day trial, or talk to an SDK expert about your project.
Codabar
Code 11
Code 25
Code 39
EAN and UPC
Telepen