Rockwell Automation 2755-L7, -L9 Scanners - Manual (Page 16)

Chapter 3
Installation Considerations
3–3
When setting up your scanner, you should attempt to have the laser line of
light nearly perpendicular to the bars and spaces of the symbol. For optimal
performance mount the scan head in a skewed position, 10
°
to 20
°
angle off
normal from the symbol, as shown in Figure 3.4.
Figure 3.4
Proper Mounting of Scan Head
Optimal angles
for scanning
beam
10
°
20
°
Optimal angles for scanning
beam
20
°
Symbol
90
°
10
°
10
°
20
°
10
°
20
°
90
°
The scan head can successfully decode symbols that are out of alignment,
provided that the projected, or apparent, bar element widths are within the
minimum widths shown in Tables 2.A and 2.B.
Symbols that are pitched or tilted up to
±
45
°
, are still readable. Skewed
symbols can also be read as long as the misalignment is less than
±
50
°
.
Figure 3.5 shows a correctly placed symbol as well as misaligned symbols.
Note: When using “A” range scanners to read labels with high paper noise,
increasing the skew to 25
°
will enhance performance.
!
WARNING: If at any time during operation an intense dot of
light is reflected onto a symbol instead of a line of light, turn the
scanner OFF with the toggle switch on the back of the scanner.
Then turn the decoder OFF.