Wincor Nixdorf TH320, Руководство программиста

Страница: 106 / 157

Programmers Guide TH320/420
98
If all of these searches fail to produce the distinct check serial number, and the check serial number
field has been specified in the parsing parameter string options, no check serial number will be
returned. If it is imbedded within the account number field, it will be returned as part of that variable
length field.
Exceptions
Some banks print the check serial number in a location that cannot be electronically distinguished without
specific exception information, although it can be visually distinguished because it is repeated in the upper
right corner of the check. For these cases, the printer can hold up to nine exceptions for specific banks in its
non-volatile memory (NVRAM), which is accessed by the read and write NVRAM commands. The specific
bank is picked out by its transit number, and the firmware will look in the exception table for a transit number
match before looking in the normal check serial number locations.
In this example, without an exception table entry, the firmware would always pick the rightmost four-
digit number as the check serial number following rule two above. The bank with the three digit check
serial number and the four digit extension after the “on us” symbol would need to be exceptionally
recognized:
txxxxxxxxxtccc-xxxxxxxxxxoxxxx
txxxxxxxxxtxxx-xxxxxxxxxxocccc
In this example, without an exception table entry, the firmware would not be able to pick out the check
serial number because it is not separated from the rest of the account number:
txxxxxxxxxtccccxxxxxxxxxxo
In this example, without an exception table entry, the firmware would not be able to pick out the check
serial number correctly, because it is imbedded within the rest of the account number:
txxxxxxxxxt xxx-ccc-xxxxxxxxxxo
Loading the exception table
The exception table begins at word 20 in NVRAM. Each entry takes five words. There is room for eight
exceptions. An application can load local exceptions into the printer using the write NVRAM command:
0x1B 0x73 n1 n2 k
which writes the two byte word n1:n2 to word k in NVRAM.
Exception table entry format
Each exception table entry consists of five words. The first two words contain the first eight characters
of the transit number by packing the low order nibble of the numeric transit number characters. For
Canadian checks, eliminate the dash and store the eight numerics.
The next three words are used as six individual bytes to tell the firmware how to interpret the MICR
characters that fall to the right of the rightmost transit symbol. Each of the six bytes is positional and
consists of two parts: character type and number.
The three high order bits of each byte mark the character type. The characters can be marked in three
ways: check serial # character, account # character, or “skip this character or symbol.”
The five low order bits of each byte contain the number of characters of that type to extract. Most
exceptions will not need to use all six bytes; in that case clear the unused bytes to zero.