Banner EZ-ARRAY USB Serial Adapter - Manual (Page 8)

6 P/N 130426 Rev. C
Banner Engineering Corp. • Minneapolis, U.S.A.
www.bannerengineering.com • Tel: 763.544.3164
A-GAGE EZ-ARRAY
Instruction Manual
Overview
Double-Edge Scan is used to detect two edges of a single
object, for example, to determine box width measurements.
Double-edge scan requires the selection of a step size: 1, 2,
4, 8, 16 or 32 beams. The sensor uses the steps to “skip” over
beams, as follows:
1. The sensor activates beam 1 (closest to the sensor display end).
2. The sensor activates the next beam, determined by the step
size. (For example, if the step size is 2, beam 3 is next; if the
step size is 8, beam 9 is next.)
3. As long as the activated beam is made (unblocked), the sensor
continues the stepping routine until a blocked beam is found.
4. When a blocked beam is found, a binary search is conducted
to find the object’s “bottom” edge.
5. When the bottom edge is found, the sensor continues to step
through the array until it finds the next unblocked beam.
6. Another binary search is performed to find the second edge.
Similar to single-edge scan, double-edge scan has some
restrictions: the object should provide a solid obstruction; the size
of the object determines the maximum step size (Figure
1-6). Double-edge scan can be used to detect up to three
objects. Like single-edge scan, double-edge scan works only
when the high-excess-gain setting is selected. When double-
edge scan is selected, the sensor object detection size varies,
depending on the step size, but edge resolution is 2.5 mm.
Figure 1-7. Finding an edge using a binary search (single-edge scan)
Emitter
Receiver
Step #1 Step #2 Step #3
Step #4 Step #5
Beam #1 of 30
blocked Beam #15
blocked Beam #23 clear
Beam #19 clear Beam #17
blocked
Step #6
Beam #18
blocked