128-A and 128-C symbology

Folks, has anyone found a way to distinguish between Code 128-A and 128-C on an imager? Customer would like to set up an automated process and have our DS340x scan one but ignore the other code (next to each other on UPS shipping labels). Since process is automated, there is no person to use the imager pick list feature. Thanks in advance.

Manny Kamer

Rob Fitton
Hi Manny, The DS3407/8

Hi Manny,

The DS3407/8 does not distinguish these codes within Code 128 (can’t pick choose it within config or ADF rules).  This would be a good GRIP entry.

Perhaps there is another part of the code that can be distinguished, such as a leading alpha, numeric, or string.

Nicholas J. Ford, PMP

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Rob Fitton
As Nick wrote, it is not a

As Nick wrote, it is not a standard feature in our products to distinguish between Code Set A and Code Set C.  It would not make a useable generic feature, because most barcode encoders and printers make the code set decisions themselves, based on the characteristics of the data.  Encoders that follow the optional algorithm in the Code 128 spec use the following decision tree: If the symbol starts with a four or more digits in a row, then set C will be picked, otherwise, the encoder looks for the first lowercase letter or ASCII control character; unless the data contains an ASCII control character before the first lowercase letter, it picks Set B, and only uses Set A if the data contains a control character first.  Following the algorithm, one would very rarely see Set A symbols.  But this algorithm is entirely optional, and for typical business data, it makes no difference whether the encoder picked A or B for non-numeric data.

The net result of the above: for general applications, it would be quite risky to set up business rules based on the starting code set of a code 128 symbol.  Maybe this customer has a custom encoder, and so the logic works for this particular customer….

However, two alternatives, that are supported by standard scanner products, may be useable in this customer’s application:

1)       If we’re lucky, the 128-C symbols are more specifically EAN/UCC-128 symbols (which do always start in Code Set C, immediately followed by a non-data symbol character called FNC1 to denote the EAN/UCC application space).  Our products provide the user with separate enable/disable control over EAN/UCC-128 vs. standard Code 128.

2)       If not, but if either the 128-C data or the 128-A data are always a different number of characters from each other, then I believe an ADF rule could be used to eliminate the symbols of the “wrong” length.

  Rick Schuessler

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