Symbol Position With Respect To A Fixed-Mount Scan Engine - Motorola SE955 Integration Manual

Symbol Position with Respect to a Fixed-Mount Scan Engine

It is sometimes necessary to mount the SE955 in such a way that it is able to read symbols that are
automatically presented to it, or that are always presented in a pre-determined location. In these situations
positioning of the SE955 with respect to the symbol location is critical. Failure to properly position the scan
engine and symbol may lead to unsatisfactory reading performance.
The SE955 can be programmed to two different scan angles. It is recommended that the position of the scan
engine is set using the widest scan angle (47°). Setting the position for the narrow scan angle (35°) and then
changing the scan angle might cause clipping of the laser beam against the housing.
Following is a series of steps you should take to ensure satisfactory operation of the SE955 in your installation:
Determine the optimum distance between the scan engine and the symbol. Due to the large variety of
1.
symbol sizes, densities, print quality, etc., there is no simple formula to calculate this optimum symbol
distance. Try this:
Measure the maximum and minimum distance at which your symbols can be read.
a.
Locate the scan engine so the symbol is near the middle of this range when being scanned.
b.
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 your system. Motorola can provide advice on
how to improve your installation.
Center the symbol (left to right) in the scan line whenever possible.
2.
Position the symbol so that the scan line is as near as possible to perpendicular to the bars and spaces in
3.
the symbol.
Avoid specular reflection (glare) off the symbol by tilting the top or bottom of the symbol away from the
4.
engine. 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 engine. See
Characteristics on page 2-12
If a window is to be placed between the engine and the symbol, the determination of optimum symbol
5.
location should be made with a representative window in the desired window position. Read the sections of
this chapter concerning window quality, coatings and positioning.
Give the scan engine time to dwell on the symbol for a minimum of 40 msec. Poor quality symbols take
6.
longer to decode. When first enabled, the scan engine may take two or three scans before it reaches
maximum performance. Enable the scan engine before the symbol is presented, if possible.
for maximum angles.
Installation 2 - 11
Exit Window