The biggest advantage of Code 128 that it is more compact than Code 39 when encoding small cap letters. Code 39 vs Code 128Īnother popular choice to encode alphanumeric characters is Code 128. For most barcode scanners this conversion has to be enabled manually, consult your scanner's manual. For instance, when the code contains the sequence "+A" the scanner must output "a". When using Code 39 Extended the barcode scanner has to convert the encoded character pairs to the intended value. a small cap letter or a control character. E.g., to encode a lowercase "a" into the code,Īll Softmatic barcode generators will automatically generate the appropriate two symbol codes if the data contains a character from ASCII character to the left, the combination to encode to the right. Character Table Code 39 ExtendedĬode 39 Extended code table. In most cases this behaviour must be activated manually in the barcode scanner. When creating Code 39 with a check digit, the check character is usually not transmitted with the actual data. The same data now with check character ("F"): A Code 39 without check character encoding "12345": Any character from the code set can be check character, even letters. 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. ![]()
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