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Host System
A
MiniScan
B
Testing The Usable Scan Length Method
Due to the variety of symbol sizes, densities, print quality, etc., there is no simple way to
calculate the ideal symbol distance. To optimize performance, use the Testing The Usable
Scan Length positioning method:
1. Measure the maximum and minimum distances at which the symbols can be read.
2. Check the near and far range on several symbols. If they are not reasonably
consistent there may be a printing quality problem that can degrade the
performance of the system. Symbol Technologies can provide advice on how to
improve the installation.
Note: Poor quality symbols (from bad printing, wear, or damage) may not
decode well when placed in the center of the depth of field
(especially higher density codes). The scan beam has a minimum
width in the central area, and when the scanner tries to read all
symbol imperfections in this area it may not decode. After a
preliminary spot is determined using good quality symbols, test
several reduced quality symbols and adjust the spot for the best
overall symbol position.
3. Locate the scanner so the symbol is near the middle of the near/far range.
d
Figure 2-12. Usable Scan Length Diagram
Bar
Code
D
Installation
1/2 L
L
1/2 L
2-15
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