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SIMPLEX 4120 NETWORK FIRE INDICATOR PANEL
OPERATOR MANUAL
SECTION 1 - SYSTEM OVERVIEW
1.1
INTRODUCTION TO NETWORKING
The Simplex 4120 Network is a system of individual Fire Alarm Control Panels
communicating on a loop as a Peer-to-Peer network (refer Figure 1). This means that every
network panel has an equal chance of putting a message out on the network. Each panel
with direct communications into the 4120 Network is defined as a "Node". Each node can
maintain the status and control of its own dedicated circuit points while monitoring and
controlling activity at other locations.
The communications scheme used by the network is based on Token Ring Communications
Protocol. In Token Ring communications, an electronic data "flag" or "token" is passed from
one node to the next. The node that holds the token is the only one permitted to talk on the
network. A node that has no messages or requests for the network simply passes the token
onto the next node. Thus, every node has an equal chance of putting a message out on the
network when needed.
A 4120 Network Node can be any of the following:
• 4120 Fire Alarm Control Panel
• 4120 Voice Fire Alarm Control Panel
• 4120-8010 Miniplex Control Panel
• 4120-8511 Universal Transponder (UT)
• 4120 Status Command Centre
• 4120-8821 2500 NDU with Command Centre
An existing 4100 Fire Alarm Control Panel or Universal Transponder can also be included in
the network by installing a 4120-0140 RS-485 Network Interface Card into a panel slot in the
existing unit and configuring the panel to accept the card.
Network information in sequentially transmitted from one node to another. At each node,
the network message is captured and either retransmitted as received, or modified before
retransmission to provide the network with a status update. The ability of the message to
circulate through the network defines network status and allows the nodes to respond
accordingly.
If a node goes off-line, its network interface module will bypass that connection until the
node is back on-line. If the wires between nodes short, open or have any other form of
communication problem, the network will isolate that section of wiring. A node that cannot
retransmit a message to the next node will transmit back to the previous node to maintain
communications and to notify the network of the node status.
In the event of multiple wiring problems, the remaining nodes will effectively "regroup" and
establish new, smaller "sub-networks" that will maintain communications among the active
nodes.
Document No: 4100-M004
June 1997
Page 1
Issue 1.0
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