Johnson Controls Metasys Intelligent Fire Network Technical Manual page 32

Choosing a
Configuration
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
Port Connections
Signal Regeneration
Wire Configuration
A B
Ports
Network Node
Node 1
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
First Point-to-Point
Connection
A B
Ports
Network Node
Node 1
On twisted pair point-to-point segments, terminating resistors are required on
each end of every segment.
Figure 9: Point-to-Point Configuration
Point-to-Point
Single wire pair connects
only two ports.
One receiver receives
signal from transmitter then
retransmits to other port.
Style 4 or Style 7
A
A B
Ports
Ports
Network Node
Network Node
Node 3
Node 2
Second Point-to-Point
Connection
A
A B
Ports Ports
Network Node
Network Node
Node 3
Node 2
Bus
Single wire pair connects
several ports.
Several receivers receive
the same signal from
single transmitter.
Style 4 Only
B A B
Ports
Network Node
Node 4
bus2
Third Point-to-Point
Connection
B A B
Ports
Network Node
Node 4
point