Rockwell Automation 2755 High Performance VLD Scanner - Manual (Page 16)

3–3 Installation Considerations
Symbols that are pitched or tilted  45
°
are still readable. Skewed
symbols can also be read as long as the misalignment is less than 
50
°
. Figure 3.3 shows a correctly placed symbol and misaligned
symbols. ➀
Figure 3.3
Positioning Terminology
Correctly positioned
symbol and package
Tilted, over square
symbol
Tilted, over square
symbol
Pitched package
and symbol
Skewed package
and symbol
Set up the scanner so the laser beam is nearly perpendicular to the
bars and spaces of the symbol. For optimal performance mount the
scanner in a skewed position, 20
°
to 30
°
angle off normal from the
symbol (Figure 3.4).
Figure 3.4
Correct Setup of Scanner
20 _
20 _
Top
Of Package
Side
Of Package
20 _
= Optimum Scanner
Mounting Angle
30 _
30 _
20 _
30 _
Skew Angle
Skew Angle
30 _
= Optimum Scanner
Mounting Angle
The scanner can successfully decode symbols that are out of
alignment if the projected, or apparent, bar element widths are within
the minimum widths shown in Tables 3.A or 3.B.
When using ”A” range scanners to read labels with high paper noise,
increasing the skew to 30
°
may enhance performance.
➀ Read ranges vary with bar code symbol quality.