Skew; Determining Read Range - Allen-Bradley 2755-LS7-SB User Manual

3–6 Designing Your Scanner System

Determining Read Range

Publication 2755-6.9

Skew

A symbol is skewed when the ends of the symbol's bars are not at
the same distance from the reader. The symbol can be read if the
distance of both ends of the bar are within the reader's read range,
and the skew is less than 40 degrees from the centerline. Unlike
pitch, skew does not affect the read range.
Note: Some skew is necessary to prevent strong reflected light
(specular reflection) from interfering with a successful read. A skew
between 20°-30° is ideal. Or skew may be combined with pitch to
give the following angle.
Reader between 20_ and
30_above or below the symbol
The readers can read bar code symbols at various distances
depending upon the type of reader and the narrowest bar code
element width (width of smallest bar or space). With picket fence
orientated labels, scan width is a factor in determining the time it
takes to read a bar code symbol.
Minimum Bar Code
Catalog Number
Width
2755-LS7-SA, 5.0 mils (0.13 mm)
2755-LS7-RA
7.5 mils (0.19 mm)
2755-LS7-SB, 7.5 mils (0.19 mm)
2755-LS7-RB
10 mils (0.25 mm)
15 mils (0.38 mm)
20 mils (0.51 mm)
30 mils (0.76 mm)
40 mils (1.02 mm)
2755-LS7-SBV, 7.5 mils (0.19 mm)
2755-LS7-RBV
10 mils (0.25 mm)
15 mils (0.38 mm)
20 mils (0.51 mm)
30 mils (0.76 mm)
40 mils (1.02 mm)
20_-30_
20_-30_
Read Range
2.0 to 3.1 in. (5.08 to 7.87 cm)
2.0 to 4.0 in. (5.08 to 10.2 cm)
2.5 to 5.5 in. (6.35 to 14.0 cm)
2.0 to 6.5 in. (5.08 to 16.5 cm)
2.0 to 7.5 in. (5.08 to 19.0 cm)
2.0 to 10.0 in. (5.08 to 25.4 cm)
2.0 to 10.0 in. (5.08 to 25.4 cm)
2.0 to 10.0 in. (5.08 to 25.4 cm)
1.25 to 4.0 in. (3.18 to 10.2 cm)
1.0 to 5.0 in. (2.54 to 12.7 cm)
1.0 to 6.0 in. (2.54 to 15.2 cm)
1.0 to 8.5 in. (2.54 to 21.6 cm)
1.0 to 8.5 in. (2.54 to 21.6 cm)
1.0 to 8.5 in. (2.54 to 21.6 cm)
Maximum Scan
Width
2.1 in. (5.33 cm)
3.6 in. (9.14 cm)
4.0 in. (10.2 cm)
5.0 in. (12.7 cm)
6.0 in. (15.2 cm)
7.0 in. (17.8 cm)
7.0 in. (17.8 cm)
7.0 in. (17.8 cm)
4.0 in. (10.2 cm)
5.0 in. (12.7 cm)
6.0 in. (15.2 cm)
7.0 in. (17.8 cm)
7.0 in. (17.8 cm)
7.0 in. (17.8 cm)