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There is a good reason for UPCA and EAN13 symbols to get confused. The UPCA symbol was first developed for the U.S. Market. Later, the same symbol was used by another organization and referred to as EAN13. On paper, both symbols do look alike and differentiation is only possible by counting the number of digits printed below the barcode symbol, that is provided printing was done correctly. UPCA symbols should have 12 printed digits and EAN13 symbols should have 13. The extra digit is printed at the left side of the symbol; it is referred to as the computed data digit and values compliant with the EAN13 standard are 1,2,3,4,5,6,7,8 or 9. UPCA symbols do not have the computed digit printed because the standard defines it as being zero at all times.
Older revision levels of the Axtel engine have always been in full compliance with the rules of the standard committees. The new engine will respond to UPCA and EAN13 read operations in a way that not only satisfies the rules of the standard committees but will also better tolerate symbols that do not follow the rules.
Axtel engines with a revision level of 4.52 or higher will act as follows:
|
UPCA
read enable |
EAN13
read enable |
Return values |
|
0 |
0 |
N. A. |
|
0 |
1 |
Symbol type is always returned as EAN13.
Digits 2 to 12 are returned as read from the image.
Digit 13, the computed data digit, may contain a 0,1,2,3,4,5,6,7,8 or 9.
The check character will be returned if EnaCheckReturn is set. |
|
1 |
0 |
Symbol type is always returned as UPCA.
Digits 2 to 12 are returned as read from the image.
Digit 13, the computed data digit, will be a zero (0) at all times.
The check character will be returned if EnaCheckReturn is set.
A "Not found" status is returned if the computed data digit contains a value of 1,2,3,4,5,6,7,8 or 9. |
|
1 |
1 |
If digit 13, the computed data digit, is zero (0), then
the returned symbol type is of type UPCA.
If digit 13, the computed data digit, is 1,2,3,4,5,6,7,8 or 9, then
the returned symbol type is of type EAN13,
digits 2 to 12 are returned as read from the image,
and digit 13, the computed data digit, may contain a 0,1,2,3,4,5,6,7,8 or 9.
The check character will be returned if EnaCheckReturn is set. |
Return status of the Axtel read engine:
|
00 |
Symbol read, check character OK |
|
42 |
Symbol read, check character incorrect |
|
48 |
Symbol not found |
Symbol layout:
Symbol content is read and returned in accordance with the committee standards:
|
Digit |
Position |
UPCA |
EAN13 |
|
1 |
Right hand side |
Check Digit |
Check Digit |
|
2 |
|
Data, LSB |
Data, LSB |
|
3 |
|
Data |
Data |
|
4 |
|
Data |
Data |
|
5 |
|
Data |
Data |
|
6 |
|
Data |
Data |
|
7 |
|
Data |
Data |
|
8 |
|
Data |
Data |
|
9 |
|
Data |
Data |
|
10 |
|
Data |
Data |
|
11 |
|
Data |
Data |
|
12 |
|
Data, MSB |
Data, MSB |
|
13 |
Left hand side |
Computed Data
= 0 |
Computed Data
= 1,2,3,4,5,6,7,8 or 9 |
As defined by standard committees, the Computed Data is derived from an algorithm that uses digits number 7,8,9,10,11, and 12 as input. If the computed value is equal to zero, then it is implied that the symbol is of type UPCA. If the computed value is equal to 1,2,3,4,5,6,7,8 or 9 it is implied that the symbol is of type EAN13, the value of zero is excluded to avoid conflicts with UPCA.
Conclusion:
As explained above, the standard committees have defined how to discriminate between UPCA and EAN13 symbols. Axtel users dealing with barcode symbols that violate these committee rules should study the return values provided in the table above in order to make the most suitable selection of enable bits for the UPCA and EAN13 read engine.
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