Rockwell Automation 2755-L7, -L9 Scanners - Manual (Page 22)

Chapter 3
Installation Considerations
3–9
Figure 3.11 further illustrates how the pitched symbol changed the Scan
Range enough to require a different scanner.
1.5 ”
2755–L7SA
3 ”
In this example, a 3
inch (7.6 cm) symbol
pitched 30
°
will
require the scanning
beam to extend an
additional 1.5 inches
(3.8 cm).
Symbol’s
Farthest
Element
11.5”
Symbol’s
Nearest
Element
10”
11.5 ”
10 ”
2755–L7SA
2755–L7SB
2755–L7SD
2755–L7SC
5
.13
25
.64
20
.51
15
.38
10
.25
5
12.7
Inches
Centimeters
10
25.4
15
38.1
20
50.8
25
63.5
30
76.2
35
88.9
Scan Range (from face of scanner)
This was the the
Scan Range and
element width at 0
°
pitch.
This is the new Scan
Range.
Pitching the symbol
changed the bar
width and extended
the scan range.
The L7SA scanner is
not recommended for
this application.
Instead, use the
L7SB.
Mils
Millimeters
Minimum Bar Width
Figure 3.11
Scan Range And Symbol Resolution Changed By Pitch
A pitched symbol will always change the minimum bar width and scan range
of the symbol. The amount of the change depends on the pitch of the
symbol.