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Code 39

This is another commonly used 1D barcode type that is known by any of the following names: USS code 39, code 3 of 9, USD-3, Type 39, and Alpha 39. Code 39 barcodes can encode both numeric and alphabetical data in parallel lines with varying widths. These barcodes are especially useful for certain industries because they are capable of encoding and decoding 26 alphabets, numbers 0 to 9, space, and six special characters (dollar sign, period, minus, percent, slash, plus, and the asterisk only at the end or beginning). Code 39 barcode is currently characterized by six narrow and three wide bars, while each encoded character consists of five bars and four spaces.

Code 39 barcode standard structure

The structure of a Code 39 format is usually as follows,

  • A start character - asterisk (*)
  • Any number of encoded characters
  • Optional checksum calculated digit
  • A stop character - second asterisk (*)

The checksum digit calculation is often done in this way;

  • The value of each character in the barcode except the Start and Stop codes (0 through 42)
  • Sum the values up
  • Divide result by 43
  • The remainder of the division is the value of the checksum character

History of Code 39

Code 39 received its name due to the fact that when a scanner reads the label, one of the 40 characters is used as a start and stop pattern, leaving 39 characters to decode. It was developed in 1974 by researchers Dr. David Allais and Ray Stevens of Intermec and later on, was expanded to a character set of 43 characters. It has also been recognized by the American National Standards Institute (ANSI) as MH10.8M-1983. Code 39 barcode has become the perfect barcode to encode small amounts of data that must contain both alphabets and numbers while retaining the linear pattern of one-dimensional barcodes.

Code 39 Uses

Code 39 barcodes can be seen in a variety of consumer products though it is the first alphanumeric label to be produced for non-retail industries purposes. You may also notice Code 39 barcodes in badges, automotive use, certain postal services, and even in medical equipment and the healthcare industry in general. It is also a common barcode used by the US Defense Department for military use, such as in their equipment.

Code 39 Pros and Cons

A Code 39 barcode generator is easy to find and does not cost an enormous amount of money. It is easy to encode and read Code 39 barcodes, capable of being done so with practically any encoding and decoding equipment and software. It is a very portable and widely used barcode. It also has the advantage of being secure and not prone to faultiness without a check number, though one is still recommended. An extended version of Code 39 exists named, Extended Code 39, making it possible for the barcode to represent the entire range of 128 ASCII characters, lowercase alphabets included. A more compact version also exists, named Code 93, with five additional special characters available. Compared to Code 39, Code 93 is smaller and more secure but it is not self-checking and will require a check number. The disadvantage is the small quantity of data available for encoding and that like any 1D barcode, it is susceptible to damage. If you wish to encode more data, it is necessary to make the Code 39 barcode longer, which in turn will make it harder to place in any surface and more time consuming to scan.

Due to it being width-encoding, a code 39 symbology can easily become unreadable in case of a slight ink spread during printing, another limiting factor of the Code 39 is its maximum number of characters possible to encode being just 43, it is impossible to fix a Code 39 barcode manually incase a system misses any input since it is an auto-correcting barcode, it also does not allow lowercase characters in the Code 39 format (it is only allowed in Code 39 extended format). Code 39 is also wider than the encryption code 128 by 30%, therefore, making it more difficult to scan and usually causes more complications for users.

GNU Barcode and labels are two free and open-source software that can issue Code 39 barcodes. You can also easily generate Code 39 barcodes using word processors such as Apple Pages, OpenOffice, LibreOffice, or Microsoft Word which are very easy alternative ways to generate the code.

For example, to encode 1234567 as a barcode, you’ll only need to open a new document in your word processor of choice, type the encoding characters (1234567) using the asterisks as start and stop points as stated earlier in the Code 39 format structure i.e *1234567*, highlight the input to change the font using the free Matthew Welch’s 3 of 9 font, increase or decrease the font size as needed and that’s it, an easily generated Code 39 barcode.

It is important to note that Microsoft Excel has no built-in barcode generator service and barcodes such as the tutorial just discussed are only generated by using barcode fonts which are available online for usage.

Code 39, although created in 1974, is notable for its lasting popularity due to the fact that it is very easy to create simply by using fonts.

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