PDF417条码简介

SAP内的PDF417

******************* PDF417 *******************

PDF417 is a two-dimensional bar code to represent datasets that are larger as the usual datasets in one-dimensional bar codes (for example, more than 1,000 characters). The entire 7-Bit ASCII character set is generally processed (binary values 1 - 127, the value 0 is not permitted).
A PDF417 bar code consists of 3 to 90 consecutive rows. Every row consists of a start/stop indicator and "code words". A code word consists of 4 bars and 4 spaces. The minimum number of code words per row is three.

Parameters for PDF417:

• Narrow module width
  Value range: 1 to 10
  This is the width for the narrowest module of a bar code, measured in pixels. Value 1 generates the "narrowest", value 10 the widest bars or spaces.

• Linear height
  Value range: 1 to 9999
  This parameter currently has no effect on PDF417. The height of a PDF417 symbol is controlled by parameter "Single Row Height" and the number of columns and rows, in conjunction with the length of text data to be encoded.

• Single row height
  Value range: 1 to 32000
  This value, multiplied by the narrow module width, returns the height of the individual rows of a PDF417 symbol, measured in pixels. Caution: Do NOT use the value 1 for this parameter

• Security level
  Value range:  0, 1-8
  This parameter controls the number of code words that are generated for error recognition and error correction. The default value 0, however, only permits error recognition but no automatic correction. If you increase the security level, the level of error correction increases with it (this increases the size of the bar code).

• Number of columns
  Here, you can define the number of the code word columns which you can use to check the width of the bar code.
  Value range:
  0 (default value) : A row/column ratio of 1:2 is used.
  Permitted values: 1 to 30

• Number of rows
  Here, you can define the number of rows which can be used to check the height of the bar code.
  Value range:
  0 (default value) : A row/column ratio of 1:2 is used.
  Permitted values: 3 to 90
  For example: If you leave both parameters set to the default value 0, the system would convert 72 code words in a bar code symbol with 6 columns and 12 rows.

• Truncation
  Value range:  X equals YES, blank character equals No
  This indicator determines if the right row indicator and the stop pattern are to be truncated (this saves space).

The following character combinations in the transferred bar code data have the special function:
\&    - This represents the end of a line (Carriage Return + Newline)
\\    - This represents a backslash (5C hexadecimal)
\0xYY - This represents a single byte with the value YY (hexadecimal)
        For example: \0x1E is output as a single byte with the value 1E (hex)
        or 30 (decimal).

Comments:
- If you specify values higher than zero for Number of columns and Number of rows, the result of both values must be less than 928.
- A bar code is not printed if the total of Columns and Rows is higher than 928.
- A bar code is not printed if the total number of code words is greater than Columns multiplied by Rows.
- You can use Truncation if it is unlikely that the bar code will be damaged.