BARCODE & SCAN OPTIONS
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10.3 Miscellaneous Barcode Information
Height of a Linear Barcode
Industry standards suggest a height of either 6.5mm or 15% of the symbol length, whichever is
greater. Symbols of less than recommended heights may cause recognition problems.
Check Characters
Yes, we recommend the use of check-characters in barcodes. Operating without check-
characters is not safe and will lead to errors that are costly to correct. Using check-characters
positively affects data integrity, especially when character density is at the limits and/or image
quality is not at its best.
Prevent Interleave 2 of 5 Partial Reading
A partial scan of an Interleave 2 of 5 symbols may decode and cause incorrect data to be read.
To prevent partial scans on long symbols, the user should include bearer bars. These bars run
along the top and bottom edges of the barcode in the scanning direction. If a partial scan of
the barcode occurs, the scanning beam will hit the bearer bar and will not decode. The bearer
bar must touch the top and bottom of all the bars and must be at least 3 times as wide.
Another solution for the short scanning problem is to fix all Interleave 2 of 5 symbols to a set
number of digits. Zeros may be used to pad the data to the set number of digits. The
application program would then be set to only accept scans of the correct number of digits.
Finally, a check digit may be used. The Interleave 2 of 5 symbology has an optional check
character that uses a weighted Modulo 10 scheme. The check character is the last character in
the symbol and should be checked by the decoder and then transmitted with the data. Since
Interleave 2 of 5 must always have an even number of digits, the leftmost character may need to
be a zero when the check character is added. The standard check digit is calculated by
assigning alternating 3,1,3,1… weights to respective data digits. These weights are then
multiplied by their respective data digits and the products are summed. The check digit is the
digit that needs to be added to the sum to make it an even multiple of 10. An example would
be if the sum of the products was 37, then the check digit would be 3.
Equation to Determining Potential Number of Stored Barcodes
The number of barcodes that may be stored in the KDC memory depends on the size of the
barcodes.
Example: In case of EAN-13, it takes up 20 bytes. The maximum number of EAN-13 barcodes
that may be saved is STORAGE_SIZE/20. For example, in case of 4MB, it may store maximum
204,800 barcodes and in case of 8MB, it may store maximum 409,600 barcodes.
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