Code 93 (also known as Code 9/3, USS Code 93, or USS 93) was developed in 1982 by Intermec as a better alternative to Code 39. The symbology can encode 47 different characters, including uppercase A through Z; the digits 0 through 9; 7 symbol characters: space, period, minus sign, plus sign, dollar sign, slash, and the percent symbol; and several special characters including the start/stop symbol. It includes support for encoding the full ASCII 128 characters set, though, like its encoding in Code 39, it is not very efficient (i.e., it requires two symbols for each ASCII 128 character). Code 93 is a variable-length symbology, with no theoretical limit on code length.
Code 93 is a linear, or one-dimensional (1D) barcode. This means the barcode is composed of a single set of varying-width vertical lines and spaces. The data in the barcode is represented linearly by these black/white patterns. The minimum black/white width is called a module. Below is a simple example.
Each character symbol in a Code 93 barcode is 9 modules wide and consists of 3 bars (black) and 3 spaces (white) (hence the name Code 93). Each bar/space can have a width of 1 to 4 modules. Both a start character and a stop character are used (the same symbol), and unlike Code 39, it includes a checksum: two characters, Checksum C and Checksum K, at the end of the data message, before the stop symbol. The symbology is further characterized as a continuous barcode, meaning that each character is adjacent to the next with no inter-character gap element. Here is our example again, diagramed for clarity:
Both checksum digits are computed as weighted modulo 47 values, with Checksum K including Checksum C in its computation.
While Code 93 is widely supported with most commercial barcode scanners being capable of reading it, the symbology has not seen much adoption. More capable and higher-density symbologies, like Code 128, were already in use when it was introduced. Since it uses two checksum digits, it is not as easy to generate and print as Code 39, the barcode it was designed to replace.
Code 93’s most common use is by the Canadian Post Office which uses it for supplemental delivery information.
The Cognex Mobile Barcode Scanner SDK supports Code 93 detection, enabling developers to gather relevant workflow and application data into their barcode scanning apps. You can download the SDK for free by registering on the Cognex Mobile Barcode Developer Network. In addition, the Barcode Scanner SDK supports a broad range of symbologies to meet your growing development needs.