Rockwell Automation 2755 Atomscan Bar Code Scanner - Manual (Page 15)

Chapter 3
Designing the System
3–4
Bar code symbols must be in the correct position as they move by the
scanner. The scan line must cross every bar, space, and both quiet zones on
the same sweep.
Correct:
All bars are
crossed by
scan line
Not Correct:
Some bars are
not crossed by
scan line
Picket Fence and Step Ladder Orientation
The primary orientation of the bar code symbol can be either picket fence or
step ladder. The orientation is not determined by the horizontal or vertical
position of the symbol itself.
•
picket fence: bars are perpendicular to the direction of travel
•
step ladder: bars are parallel to the direction of travel
Figure 3.2
Picket Fence Orientation
Direction of Travel
Scanner Mounted
On Side of Conveyor
Direction of Travel
Scanner Mounted
Above Conveyor
Symbol Orientation