High-Speed NFN Manual —
P/N 54013:C4 8/8/2019
11
NFPA Class X Configurations
Network Configurations
In an NFPA Class B fiber-optic system, a single break will result in loss of communication between network nodes. In Figure
3.2, the
fragment to the left of the break cannot receive information from the fragment to the right of the break. The fragment to the right of
the break cannot receive information from the fragment to the left of the break.
3.3 NFPA Class X Configurations
High-Speed Noti•Fire•Net is capable of communicating using an NFPA Class X SLC (refer to Figure 3.3). Under this style of operation,
a single open, wire-to-wire short, wire-to-wire short and open, wire-to-wire short and ground, or open and ground will not result in frag-
mentation of the network. Communication will continue throughout any of the aforementioned circumstances, while the system displays
a trouble condition. A single ground does not affect communication, but is detected. Class X operation may also be achieved using fiber-
optic cable or mixed media (wire and fiber).
A
B
A
B
A
B
A
B
These two nodes continue to
communicate with each other, but
cannot communicate with the
other two nodes.
These two nodes continue to
communicate with each other,
but cannot communicate with
the other two nodes.
fo
br
ea
k
.wmf
Break
Network
Node
Network
Node
Network
Node
Network
Node
Figure 3.2 Fiber-Optic Class B System Break
A
B
A
B
A
B
A
B
A
B
A
B
Note: High-Speed Noti•Fire•Net
network wiring is power-limited.
Figure 3.3 Class X Configurations
NFPA Class X SLC With Regeneration
(Twisted Pair Wire, Point-to-Point
Connections or Transmit and Receive
Fiber Optic Cable Pairs)
Network
Node
Network
Node
Network
Node
Network
Node
Network
Node
or
Repeater
Network
Node
Network
Node
or
Repeater
Network
Node
= Network Node or Repeater
with two ports, A and B
= Network Node
with two ports, A and B