User Manual

36 AR 400 Reader User’s Manual  2003-2004 Matrics, Inc.
Section 6. Notification of Events
Events Overview
The AR 400 Reader generates several types of events: Visibility and Threshold Events that report tag
activity; and Network Status and Exception Events that report device/system activity. If you want to be
notified when particular events occur, you can choose (subscribe to) these events via the Event
Notifications page. You may also choose whether or not you want to receive any event notifications at all.
Visibility Events
There are three types of Visibility Events that are generated when changes in tag visibility occur:
 New Tag Event— A New Tag Event is a special case event generated to notify you when a new tag
appears for the first time. A new tag is one that has never been seen before, and has not previously
been known to the Reader. You can then commission the tag (or associate an User ID and a threshold
rule to the tag.)
This event should be processed in a timely fashion to give meaningful results, so set the Notify
option to Immediate (the default for this event type). If you don’t want to be notified when this type
of event occurs, set the Notify option to Never, in which case the event is promoted to a generic
Visibility Changed Event.
 Tag Not Visible Event—A Tag Not Visible Event is a special case event generated to notify you
when a tag is not currently visible to any Read Point. For example, if a tagged item is removed from
a shelf and is out of RF range (not being seen by any Read Point), then a Tag Not Visible Event
would apply. The Event reports where the tag was located when last visible to the system.
Since there may be cases, in the normal course of operation, that a tag has transient periods when it is
changing visibility in the system, set the Notify option to Moderated to smooth out temporary
conditions, and generate an event only when the tag is no longer being actively tracked. (The AR 400
Reader still knows about the tag, but it is not visible to any Read Point.) If you don’t want to be
notified when this type of event occurs, set the Notify option to Never, in which case the event is
promoted to a generic Visibility Changed Event.
 Visibility Changed Event—A Visibility Changed Event is a generic event (not as specific as a New
Tag or Tag Not Visible Event) generated any time that the visibility of a tag changes. The visibility
change may be due to more, less, different, or even no Read Points being associated with a tag. For
example, if a tagged item moves from a shelf on aisle 2 to another shelf on aisle 4 (visibility changes
from one Read Point to another), then a Visibility Changed Event would apply.
Note: If you have enabled Tag Not Visible Events, then a tag not currently visible to any Read
Point(s) will generate the more specific Tag Not Visible Event instead. Likewise, a New Tag Event
will be generated for the first visibility change when applicable.