Microscan MS-890, User Manual

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MS-890 Industrial Automation Scanner User Manual
A-31
Appendices
Improving Decode Rate
After changing any of the parameters described in this section, recalculate the number of
decodes.
Scan Rate
Scan rate is a function of motor speed and is adjustable. A slower scan rate may allow
greater symbol range and/or higher decode rates, but at the cost of fewer scans per
symbol and scan width.
Range
Adjusting the symbol’s range, if possible, is one of the quickest and most effective ways to
improve decode rates. However, in some applications you may need to select a less than
optimum range, or one that is beyond the fringes of the ranges.
Scan Width
Increasing scan width will increase the number of scans in a picket fence oriented application.
Scan width is linked with scan range and changing one will usually require a change in the
other.
Symbol Speed
Applies to both picket fence and ladder oriented symbols. If your application allows it,
slowing symbol speed (the time in seconds that a symbol is fully within the scan width of
the scanner) is an effective way to increase the number of decodes.
Raster Height
When using the raster features, you can increase the decode rate by decreasing the
height of the raster image.
Raster Sweep Rate
Slowing the number of sweeps per second to the minimum needed will result in more scan
lines passing over the symbol and a higher decode rate.
Laser Framing
Narrowing the laser frame may not increase the decode rate, but it will minimize the
opportunity of extraneous reads.
Symbol Dimensions, Symbol Density, and Symbol Ratio
Not usually an option in most applications, but changes to symbol parameters can affect
number of decodes calculations and possibly decode rates.
If your application allows it, shortening the length of a picket fence symbol means the
symbol will be in the scan range longer and hence receive a greater number of scans.
Increasing the height of a ladder symbol means it will receive more scans. Changing
symbol density and/or symbol ratio is another way ranges, decode rates, etc. can be
altered.
Gain and Tracking
These adjustments, typically made by qualified technicians, are referenced in the Scanner
Setup menu (see Defaulting/Saving/Initializing on page A-18). Changes to tracking will
generally have a limited affect on decode rates.