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When printing barcode symbols we strongly recommend the use of check-characters for verification. Some barcode printers do not support check-character generation. That forces application programs to calculate the check-character and to append it to the character string for printing. To calculated a Code 39 check character:
1) Add up all characters in the string.
Values: 0=0 to 9=9, A=10 to Z=35, -=36, .=37, space=38, $= 39,/=40,+=41 and %=42
2) Divide the sum by 43.
3) The remainder is the check character for the string. (Sum Modulus 43)
Different print formats are:
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19AZ |
Net string only. |
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19AZC |
Net string with check character. |
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*19AZC* |
Start character, net string, check character, and end character. |
Note:
1. The * is used by some printers as a place holder for the start and end character.
2. The * is illegal in a net string or check character position.
3. The AX-4 write engine automatically inserts the * as start and end characters.
Compute check character for example string 19AZ:
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01 |
Numeric value for digit 1 |
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+ 09 |
Numeric value for digit 9 |
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+ 10 |
Numeric value for character A |
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+ 35 |
Numeric value for character Z |
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= 55 |
Total
Divide 55 by 43.
The remainder of this operation is 12.
The numeric value of 12 equals character C. (see list above)
Append a C to the string as the check character. |
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