Details
Event:
Different characters are reported when you define more than one Config to mix OCR and T7 reads.
The user's wafer is engraved with OCR characters and T7 symbols, where the user defines OCR and T7 in a separate Config and expects the read to succeed on any Config, but because the number of characters reported when read in OCR and when read in T7 differs, the upper PLC is incorrectly determined.
Probable Causes:
The two-digit SEMI checksum character appended to OCR character for the checksum results in a two-character long string being reported when scanned by OCR, whereas the decoded string does not have a checksum because T7 does not require a checksum, so both return a different number of characters.
Solution:
This is a problem that occurs occasionally. In order to avoid this problem for some users, it is very rare, though there were cases in which T7 included SEMI checksum characters that were originally not added, and they were encoded in T7.
Different characters are reported when you define more than one Config to mix OCR and T7 reads.
The user's wafer is engraved with OCR characters and T7 symbols, where the user defines OCR and T7 in a separate Config and expects the read to succeed on any Config, but because the number of characters reported when read in OCR and when read in T7 differs, the upper PLC is incorrectly determined.
Probable Causes:
The two-digit SEMI checksum character appended to OCR character for the checksum results in a two-character long string being reported when scanned by OCR, whereas the decoded string does not have a checksum because T7 does not require a checksum, so both return a different number of characters.
Solution:
This is a problem that occurs occasionally. In order to avoid this problem for some users, it is very rare, though there were cases in which T7 included SEMI checksum characters that were originally not added, and they were encoded in T7.
