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Code 39 barcodes should all start and finish with the same pattern that represents the * or asterisk character, however sometimes printers forget to include these characters and the result is a barcode that doesn’t actually fit the Code 39 barcode specification. It is possible to read such barcodes but they do have a significant problem because they read different values forwards and backwards.

Take the following example:

When decoded the right way up it reads ABCDEFG, but upside down it reads 3045781. This is because each set of bar and space pattern used in the Code 39 symbol set can have 2 meanings depending on whether it is read from left to right or right to left. In this case the A is the same as the 3 when read backwards.

Anyhow, using the Softek Barcode Reader SDK you can decode such barcodes by changing the following settings:

First, remove the requirement for the start/stop character:

Code39NeedStartStop = False or 0

Fix the scan direction to left to right (assuming your barcodes are not upside down):

ScanDirection = 1

Also, set the MinLength property to the maximum size possible for your barcodes:

e.g MinLength = 7

And increase the MinOccurrence property to at least 5 to avoid false positive reading:

MinOccurrence = 5