Welch Allyn Scanteam 3700PDF, Technical Manual

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Printing PDF417 Labels C–1
Printing PDF417 Labels
C
C.1 Printing PDF417 Labels for Improved Readability
PDF417 was designed to allow great flexibility in printing, making it possible to print
labels to meet a variety of requirements. This appendix describes five label parameters,
demonstrates how these parameters affect the printed symbol, and presents suggestions
for choosing the parameters for maximum readability. The goal is to produce labels that
are easy to scan.
C.2 PDF417 Label Parameters
The following parameters may be chosen when printing PDF417 symbols:
1.
X dimension
2. Y dimension, or row height
3. Number of columns of data (1–30)
4. Number of rows of data (3–90)
5. Error correction level (0–8)
C.2.1 X Dimension, Y Dimension
Codewords are the building blocks of PDF417. Each codeword is comprised of four bars
and four spaces and can be divided into 17 equal modules. The X dimension is the width
of a single module. The Y dimension is the height of the codeword.
C.2.2 Number of Columns and Rows
Every PDF417 label is a matrix of codewords. You pick the number of columns (1–30)
and rows (3–90) in the matrix. For example, to print a label which encodes 216
codewords, you could choose 9 rows by 24 columns to equal 216 codewords, or 18 rows
by 12 columns to equal 216 codewords. The resulting labels will have very different
shapes, but each encodes the same message. This feature allows you to fit a PDF417
label to a desired shape. Because of this arrangement, the Y dimension can be called the
row height.
C.2.3 Error Correction Level
PDF417 employes powerful error correction techniques. The decoded message will not
contain any errors, even when the label is damaged. Extra codewords, called error
correction codewords, are added. Message codewords fill the top rows of the matrix, and
error correction codewords fill the bottom rows of the matrix.