Instruction manual

4-10 Packet Reference Manual
Using Check Digits
Check digits are typically used to ensure that a text or bar code field scans correctly. If you
apply Option 31, the printer calculates a check digit. A check digit scheme determines how the
printer calculates a check digit. When you define a check digit scheme, you assign a number to
identify it. This number is later entered in R4 (check digit #) when you apply Option 31 to
a field. You can use check digits with text or bar code fields. Check digit calculations are
performed on numeric data only.
Do not use check digits with price fields. Do not define a check digit scheme for UPC, EAN,
Code 39 (with the MOD43 check digit), and Code 93 bar codes, because they have predefined
check digits.
Syntax {A,selector,action,device,modulus,fld_length, D/P,
"weights" | }
A1. A Check Digit Header.
A2. selector Assign a number from 1 to 10 to this check digit formula.
A3. action The action to perform. Enter A to add the check digit scheme.
A4. device Format storage device. Use R (Volatile RAM).
A5. modulus Number from 2 to 11. The modulus is used to divide the sum of products or the sum
of digits.
A6. fld_length The maximum number of characters the field will contain. Range: 0 to 2710.
A7. D/P Algorithm. The algorithm determines how the check digit is calculated. Options:
D sum of digits
P sum of products
A8. “weights” String of digits used for calculation. A weight string is a group of two or more
numbers that is applied to a field. The number of digits in this string should equal
the number in fld_length. Enclose in quotation marks. Range: 0 to 2710.
Example {A,1,A,R,10,5,P,"65432" | }
Adds check digit scheme number 1 to the printer’s memory. The modulus is 10, the maximum
number of characters in the field is 5. The check digit is calculated by using the Sum of
Products and the string of digits used in the calculation is “65432.”
Sum of Products Calculation
This is an example of how the printer uses Sum of Products to calculate a check digit for this
data:
5 2 3 2 4 5 2 1 9
1. Weights are applied to each digit, starting with the last digit in the weight string. They are
applied right to left, beginning at the right-most position of the field. Remember, a weight
string must contain at least two different numbers. This example has a weight string of
1,2,3,4:
field: 5 2 3 2 4 5 2 1 9
weight string: 4 1 2 3 4 1 2 3 4