Appendix B > 128APPENDIX BCOMPUTATIONAL BARCODESThe Barcode feature provides access to scalable, configured barcode printing via specialPCL5 font selection sequences. Such barcodes can be printed in a variety of sizes androtations, with automatic generation of check characters, etc. upon request. The barcodesare rendered algorithmically; there are no “barcode fonts” used.This feature offers better barcode support than bar coding fonts, due to the fact that barthickness, wide-to-narrow ratios, check digit support, etc. can be supported in ways thatare not available with bar coding fonts. Also, there are some barcodes (like Interleaved 2of 5) that cannot conveniently be supported with barcode fonts.HOW BARCODING WORKSThe use of this printer’s PCL5 bar codes requires the user to insert certain special fontselection commands in the PCL5 data stream. Special typefaces are reserved for activationof the processor.There are several steps that are taken in order to process barcode data.1. Activation is by selection of one of the reserved typeface numbers in the standardPCL typeface selection escape sequence (s#T. In general, the reservedtypefaces are all in the range of 24580 to 24800.Additional barcode parameters are specified by way of the other standard fontselection commands (see page 129 for descriptions of how these commands areinterpreted):> (s#P> (s#H> (s#V> (s#S> (s#B2. After the barcode parameters have been selected, subsequent text data will begathered for processing. The end of bar code data is determined according to the barcode type:In general:If the barcode numeric only data, the end of barcode data is indicated by space/CR/LF/FF/Escape code.If the barcode is alphanumeric, end of data is indicated by CR/LF/FF/Escape code.Some bar code formats support use of the full 128-character ASCII character set.(128A, 128auto, EAN/UCC128). If you want to print special characters (ASCII code< 32) with those bar codes, a Transparent Print Data PCL sequence (Esc&p#X,where # is replaced with the number of following data bytes) must followimmediately the font selection sequence. This is the only way to know how manycharacters have to be printed as bar codes. Please analyse the sample Code/EAN/UCC 128 test files for more information.3. Once the data is gathered, it is analysed to verify it fits in the bar code specs:Correct data size EAN 8/13 and UPC A/E have fixed lengths etc...).Valid data: some systems, like UPC-E, accept only specially structured data.4. Then the barcode data is compressed, if necessary. Some code systems, like UPC-E,print compressed data, while ours allows the barcode data to be precompressed (6-characters input) or uncompressed (10 characters input). If uncompressed data is
