User Manual

“Halo” System: Communication Protocol 970-00002-000
EXI Wireless Systems, Confidential Page 9 of 33 July 27, 1999
3.2.1. Controller
The Controller is used to monitor and control the area in which it is installed, usually near the door. It
generates the “field of coverage” around itself and any Tag entering this field will be registered by the
Controller (Tag In the Field (TIF) alarm). The other Controller’s task is to register if any of the Tags are
sending TIC alarm. When the Tag enters this mode depends on particular type of the Tag, but the
communication principle is always the same.
These alarms are passed to the Host via “RS-485 Interface Module” (RIM) which serves as an interface to
the RS-485 based network.
The Controller can be programmed to respond or not to a particular Tag, and when it does respond it can
take certain actions; lock / unlock the door, activate audible alarm and control any external device via the
relay.
3.2.2. Elevator
The Elevator node is special version of the Controller node. While the Controller is intended to cover the
area near the door, the elevator application has to be approached differently to avoid false alarm triggering
due to somebody just walking near the elevator and to avoid installing separate Controller on the every
floor, just to mention two most important reasons.
The Elevator communication to the Host is almost identical to the Controller.
3.2.3. Receiver
The Receiver is a node which will respond to TIC alarms only. It has limited control functionality (one
relay) and it can not receive any commands from the Host. The idea behind the Receiver concept is to
blanket the building with low cost nodes in order to reliably register TIC alarm. The Controllers could be
used for this purpose but they are not cost effective.
The Receiver communicates with the Host in similar fashion as the Controller but with limited
functionality.
3.3. Sensors
Tags are the only sensors in this system (if we disregard door open / closed sensing by a Controller and an
Elevator). There could be different types of tags within the system as discussed earlier, but all of them have
common characteristic to be able to communicate to the Controllers, Elevators or Receivers by using
common protocol.
3.4. Communication
There are 4 different communication protocols used in this system and the difference among them is
determined mostly by communication media used.
Figure 2
HOST TAGCONTROLLERRIM
485 Comm
Control Lines
Comm
Weigand
Comm
RF Comm