The characters are summed up, modulo divided by 43, the reminder is the checkĬharacter. Check Digit for Code 39Ĭode 39 uses a modulo 43 checksum scheme. To encode a "*" with Code 39, use the combination "/B" (see table below). Formatting a string like "*12345*" with a Code 39 barcode font will then create a valid barcode (albeit without check digit). When using a barcode font for Code 39, the start/stop-character is traditionally mapped to the "*" character. Usually, the barcode generator will add those two characters to the symbol automatically. ,Ĭode 39 uses an identical non-encodable symbol for both start and stop characters. The bit pattern of the start / stop character is at the '*' slot. First item is the character, followed by nine elements for bars and spaces '0' is a narrow element, '1' is a wide element. The Code 39 bit pattern (JavaScript array syntax). Smaller ratios will increase the density of the code (making it smaller for given data) but can make scanning the code more challenging.Ī code with a ratio of 2.0 ("High Density" or "HD"):Ī code with a ratio of 2.5 ("Medium Density"), best choice for most applications:Ī code with a ratio of 3.0 ("Low Density" or "LD"): Code 39 / Code 39 Extended Bit Pattern Likewise, the ratio of wide to narrow bars can be anywhere between 2.0 and 3.0. We recommend a module width of 0.5mm and a module height of 20mm for most applications. Printing: Thermal direct, thermal transfer, laser, inkjet, dot-matrixĬode 39 Sizes, Low Density vs High DensityĬode 39 has very lenient specifications and can be created with module widths ranging from 0.1 to over 5mm, same goes for the height of the code.Scanning: CCD / Laser scanners, imagers, scanner apps.Generators: Stand-alone, barcode fonts, barcode extensions.Modes: Standard, Extended (full ASCII character set).This naming scheme is derived from Code 2-of-5 which has five elements, two of which are wide.Ĭode 39 is mainly used for warehousing, in Germany and other countries it is also used for pharmaceutical products. Instead, it's short for "three of nine", from the fact that an individual symbol has nine elements (bars and spaces), three of which are wide. The "39" in the symbology's name does not refer to the size of the encodable character set, this is a common misconception. If those combinations of symbols are used the code is referred to as Code 39 Extended. ![]() ![]() Two symbols the full ASCII character set can be encoded including special characters like currency symbols. Originally developed in the 1970s, Code 39 encodes numbers, capital letters (A-Z) and some special characters.
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