User manual

V002450_25_CR1200-CR2-CR3-CR2500-CR3500_Interface_Configuration_Document_CLIENT.docx
2011-04-27 Page 54 of 65
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The In Line Group must always be ended with an In Line Group End control code.
12.4.12 In Line Group End (12)
The In Line Group End control code is used to terminate an active In Line Group definition.
12.4.13 Checksum (13)
Checksums may be used to reduce the probability of misreads involving OCR. The OCR decoder
supports a number of options associated with checksums. The user may specify the type (block or row),
the weight scheme (1, 12, 13, 137) and the modulo value of the checksum (6-36). The byte immediately
following the Checksum control code defines the type of checksum that will be used:
Bit Position(s)
Meaning
7,6: Weight Scheme 00: Weight Scheme: 1
01: Weight Scheme: 12
10: Weight Scheme: 13
11: Weight Scheme:
137
5: Checksum Type
0: Row
1: Block
4-0: Modulo Value
Checksum Modulo - 5
Row Checksums perform a checksum calculation on all characters preceding them up to the first char on
the same row. Block Checksums perform a checksum calculation on all characters up to the very first
character in the template; they span multiple rows.
The 5 bit Modulo Value stores the Checksum Modulo – 5. The stored number may range from 1, which
is a Checksum Modulo value of 6, to 31, which describes a Checksum Modulo of 36. A Modulo value
of 0 (Checksum Modulo of 5) is illegal.
The characters within a checksum field have a numerical value that is used in the checksum calculation.
Digits are converted to their numerical value (0-9), while Upper case letters range from 10 for an ‘A’ up
to 36 for a ‘Z’. All punctuation characters currently have a value of 0 for checksum purposes. However,
they do count as a spot for determining the weight values that will be used in calculating the checksum.
The Weight Scheme defines how the values described above can be changed based on their character
position. The default weight scheme is 1. This means that the checksum is based only on the character
value and is not dependent on its position. The other weight schemes multiply the character value by a
repetitive weight value that helps in identifying characters that have had their column locations
switched. The 4 weight schemes are:
Weight Scheme Multiplier values
1 1,1,1,1,1,….
12 1,2,1,2,1,2,….