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OCR Programming

8-14 PowerScan

7000 2D

2-1-2-1 Weighted Modulo 10 Check Character

Starting with the check character and working backward through the

message, the imager applies a multiplier of 1, then 2, then 1, then 2, and

so on. When the result of the multiplication is greater than 9, add both

digits to the running sum. This is often referred to as the LUHN for-

mula. One common application of the LUHN formula is validate credit

card numbers. This is the modulo 10 checking scheme used in MSI

Code and in Code 32 Pharmaceutical (PARAF). To apply this weighting

scheme, set the OCR check character to "0123456789x2x1" or scan the

following symbol:

Example: Scan the 2-1-2-1 Weighted Modulo 10 Check Character symbol. Also enter

the OCR template:

ddddddc

Then scan the string below:

0128454

The reader performs the check character computation below:

(0 x

1 + 1 x 2 + 2 x 1 + 8 x 2 + 4 x 1 + 5 x 2 + 4 x 1) modulo 10

= (0 + 2 + 2 + (1 + 6) + 4 + (1 + 0) + 4) modulo 10

= 0

Since the result is zero, the message is considered to be valid, so the

reader outputs the message: 012845

2-1-2-1 Weighted Modulo 10

Check Character

Datalogic PowerScan 7000 2D Product Reference Guide

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