Motorola SYMBOL MINISCAN MSXX04 - Manual (Page 34)

2 - 10 Symbol MiniScan MSXX04 Series Integration Guide
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. Motorola can provide advice on how to
improve the installation.
3. Locate the scanner so the symbol is near the middle of the near/far range.
4. Center the symbol (left to right) in the scan line whenever possible.
5. Position the symbol so that the scan line is as near as possible to perpendicular to the bars and spaces in the
symbol.
6. Avoid specular reflection (glare) off the symbol by tilting the top or bottom of the symbol away from the scanner.
The exact angle is not critical, but it must be large enough so that if a mirror were inserted in the symbol
location, the reflected scan line would miss the front surface of the scanner. For the maximum allowable angles
refer to the Skew, Pitch and Roll angles listed in each MiniScan Technical Specifications table.
7. If an additional window is to be placed between the scanner and the symbol, determine the optimum symbol
location using a representative window in the desired window position.
8. Give the scanner time to dwell on the symbol for several scans. When first enabled, the MiniScan may take two
or three scans before it reaches maximum performance. Enable the MiniScan before the symbol is presented,
if possible.
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.