Miscellaneous Barcode Information; Height Of A Linear Barcode; Check Characters; Prevent Interleave 2 Of 5 Partial Reading - KoamTac KDC200 User Manual

A.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 symbol may decode and cause incorrect data to be read. To
prevent partial scans on long symbols, you should include bearer bars. These are bars that 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 can 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
which 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 needed 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.
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KDC200 User Manual