Johnson Controls FIRE-MON-17, Technical Manual

Page: 32 / 72

32 IFC Networking—Metasys Intelligent Fire Network
FN nodes using twisted pair wire can either be configured in the
point-to-point (preferred) or bus configuration. Fiber optic cable
can only be configured in point-to-point. The point-to-point configuration
allows for a greater distance between nodes and a clearer communication
line, since the message is regenerated between Ports A and B. The bus
configuration passes along the same message from Port A on the first node
to Port A on the second node without regeneration. Over long distances,
the message quality on a bus configuration can deteriorate.
Both the point-to-point and the bus configurations have different distance
capabilities.
Table 12: Point-to-Point vs. Bus
Feature Point-to-Point Bus
Port Connections
Single wire pair connects
only two ports. Single wire pair connects
several ports.
Signal Regeneration
One receiver receives
signal from transmitter then
retransmits to other port. Several receivers receive
the same signal from
single transmitter.
Wire Configuration Style 4 or Style 7 Style 4 Only
Network Node
Node 4
bus2
Network Node
Node 3
Network Node
Node 1
Network Node
Node 2
A B
Ports
A B
Ports
A B
Ports
A B
Ports
On twisted pair bus configuration, terminating resistors are on the end nodes.
Remove all others.
Maximum end-to-end bus length (without repeaters) should not exceed 100 ft.
Figure 8: Bus Configuration
point
Network Node
Node 4
Network Node
Node 3
Network Node
Node 1
Network Node
Node 2
A B
Ports
A B
Ports
A B
Ports
A B
Ports
On twisted pair point-to-point segments, terminating resistors are required on
each end of every segment.
First Point-to-Point
Connection
Second Point-to-Point
Connection
Third Point-to-Point
Connection
Figure 9: Point-to-Point Configuration
Choosing a
Configuration