AML M2500 Decoder - Manual (Page 71)

G - 2
OPTIONAL CHECK DIGIT:
Interleaved 2 of 5 may contain an optional check digit. The reader supports two
types of check digits:
1. Uniform Symbology Specification (USS) - calculated as modulo 10 check
digit based on 3-1-3 weightings.
2. Optical Product Code Council (OPCC) - calculated as modulo 10 check digit
based on 2-1-2 weightings.
USS CHECK DIGIT CALCULATION:
1. From right to left, sum the digits in the odd positions.
2. Multiply this sum by 3.
3. From right to left, sum the digits in the even positions.
4. Add this sum to the product of step 2.
5. The modulo-10 check digit is the smallest number which when
added to the sum of Step 4 produces a multiple of 10.
EXAMPLE: USS check digit. Sample bar code data: 513827
1. Sum 7 + 8 + 1 = 16
2. Multiply 16 x 3 = 48
3. Sum 2 + 3 + 5 = 10
4. Sum 48 + 10 = 58
5. 58 + 2 = 60 (check digit = 2)
Therefore: Data + check digit = 5138272
NOTE: A leading zero will be required to make it an even
number of characters. The resulting bar code will be:
05138272
OPCC CHECK DIGIT CALCULATION:
1. From right to left, assign every digit a weighting factor from the
sequence: 2,1,2,1,2,1,2,1,...
2. Multiply each digit by its weighting factor.
3. Sum the products in step 2, treating two digit products as the sum
of the individual digits.
4. The check digit is the smallest number which when added to the
sum of step 3 produces a multiple of 10.
EXAMPLE: OPCC check digit
Sample bar code data: 020489713
1. Assign weighting factors: 020489713 212121212
2. Calculate the products: 0 2 0 4 16 9 14 1 6
3. Sum the products: 0+2+0+4+1+6+9+1+4+1+6 = 34
4. 34 + 6 = 40 (check digit = 6)
Therefore: Data + check digit = 0204897136