User's Manual

BARCODE & SCAN OPTIONS
177
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