Rockwell Automation 2755 AtomScan Bar Code Reader - Manual (Page 23)

3–3 Designing Your Scanner System
Publication 2755-6.9
Bar code symbols must be in the correct position as they move by
the reader. 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 but rather by the
direction of travel of the bar code past the reader. With picket fence,
the bars are perpendicular to the direction of travel and with step
ladder, the bars are parallel to the direction of travel.
Picket Fence
Step Ladder
Direction of Travel
Symbol Orientation