Banner EZ-ARRAY USB Serial Adapter - Manual (Page 7)

P/N 126701
5
Banner Engineering Corp. • Minneapolis, U.S.A.
www.bannerengineering.com • Tel: 763.544.3164
A-GAGE EZ-ARRAY
QuickStart Guide
Overview
1.6 Scanning Method
The receiver may be configured for one of three scanning
methods:
• Straight scan
• Single-Edge scan
• Double-Edge scan
Straight Scan is the default mode, in which all beams are
scanned in sequence, from the display end to the far end
of the array. This scanning method provides the smallest
object detection size. Straight scan is used when low-contrast
sensitivity is selected or when single-edge and double-edge
scan cannot be used. The edge resolution is 5 mm (0.2"). When
low-contrast sensing is selected (used when measuring semi-
transparent objects), the minimum object detection size is 5 mm
(0.2") diameter. When high-excess-gain sensing is selected, the
minimum object detection size is 10 mm (0.4"). See Figure 1-5.
Single-Edge Scan is used to measure the height of a single
object. A good application for this scanning method is box
height measurement. For single-edge scan, the receiver always
activates the first beam channel (or “bottom” beam, nearest the
display). If the first beam is blocked, the sensor will perform a
binary search to hunt for the last beam blocked. Single-edge
scan works as follows:
1. The receiver scans only the first beam until that beam is
blocked.
2. When the first beam is blocked, the sensor looks to see
whether the middle beam is blocked or made (unblocked).
3. If the middle beam is made (unblocked), the sensor checks
the bottom quarter beam; if the middle beam is blocked, the
sensor checks the top quarter beam. (This is called a binary
search; see Figure 1-6.)
4. The routine continues to “narrow the field” until the edge is
found.
Figure 1-6. Finding an edge using a binary search (single-edge scan)
Figure 1-5. The effect of scan mode/step size on minimum object detection size and edge resolution
Scan Mode
Straight Scan
Single-Edge
Scan
Double-Edge Scan
Low-
Contrast
High-
Excess-Gain
Step Size (Number of Beams)
1 2 4 8 16 32
Minimum Object
Detection Size* 5 mm
(0.2") 10 mm
(0.4") 10 mm
(0.4") 10 mm
(0.4") 20 mm
(0.8") 30 mm
(1.2") 50 mm
(2") 90 mm
(3.6") 170 mm
(6.8")
Edge Resolution
5 mm
(0.2") 5 mm
(0.2") 2.5 mm
(0.1") 2.5 mm
(0.1") 2.5 mm
(0.1") 2.5 mm
(0.1") 2.5 mm
(0.1") 2.5 mm
(0.1") 2.5 mm
(0.1")
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
*MODS determined using a rod target object