Circular Code 39

Circular Code 39 shares the same properties as the Code 39 - Full ASCII barcode symbology. Additionally, it uses special two-character combinations from the 43 character set to allow for the representation of all 128 ASCII characters. In other words, you can encode any of the standard (not the extended) characters from the computer's keyboard into a barcode, as well as the ASCII control characters.

While Circular Code 39 has the advantage of representing all 128 ASCII characters, it does sacrifice barcode character density to do so. When encoding into Code 39 barcodes any characters that are native to the 43 character set, your barcodes do not undergo any degradation in character density. However, since each Full ASCII character is represented by a 2-character combination, the more of them you use, the more space you need for your barcodes. For example, the word "SEAGULL" is encoded into barcode as *SEAGULL*, but the word "seagull" is encoded into barcode as *+S+E+A+G+U+L+L*, which takes about twice as much space.

Circular Code 39 also has a "start/stop" character. This character is used at both the beginning and the end of the barcode message to signal a barcode reader that a Circular Code 39 barcode has been scanned. This character is commonly designated as an asterisk (*), but you may choose to have no start/stop characters at all or choose to let the data source specify the start or the stop character, or both. The start and stop character are not transmitted as part of the barcode, and is not included in any check digit calculations.