Appendix H Object Detector - Microscan MS-890 User Manual

Object Detector
Appendix H — Object Detector
In a typical operation, a scanner will wait for symbol data only during a triggered read
cycle. A read cycle is initiated by a "trigger" and can be in the form of a serial command
from the host (internal trigger) or a signal from an object detector (external trigger).
When an object detector (also called a sensor, package detector, etc.) is used, it is set up
so that its beam will bounce off the approaching object and the resulting pulse will be sent
to the scanner to begin the read cycle. Typically, a detector is positioned so that it will
detect the presence of an object before its symbol can be scanned.
An object detector is mounted in almost any position relative to the object as long as:
(1) the object passes within range of the detector and
(2) direct or reflected light from the detector does not interfere with the scanner's reception.
As the item continues to move down the line, its symbol moves into the scanner beam and
is read by the scanner.
The drawing below shows a symbol in the picket fence direction with the object detector
positioned so as not to cause interference.
A-22
Object Detector Operation
MS-890 Industrial Automation Scanner User Manual