Lonworks Network Connection; Network Cable; Network Limits - Lennox LGH 036 Installation Instructions Manual

LonWorks Network Connection

The LonTalk module has an FTT−10A Free Topology
Transceiver for network communication. The FTT−10A
transceiver network supports free topology wiring and will
accommodate bus, star, loop, or any combination of these
topologies. The module can be located at any point along
the network wiring. This capability simplifies system instal-
lation and makes it easier to add nodes when required.
LonWorks Network Cable
The LonWorks TP/FT−10 network requires Echelon quali-
fied twisted−pair communication cables such as Belden
8471 or NEMA Level 4 cables. Other Echelon approved
equivalent cables may also be used depending on the ap-
plication. The Belden 8471 or NEMA Level 4 cables are
rated for plenum use.
The network cable should be routed using best practices to
avoid induced noise. Do not route alongside power lines, or
in proximity to high voltage or high frequency devices, such
as ignition controls and variable frequency drives. The av-
erage temperature of the wire must not exceed 131°F
(55°C).
Network Limits (Free Topology)
The LonWorks TP/FT−10 free topology network is limited
Termination
Termination
Termination
LOOP
TOPOLOGY
Figure 8. Free Topology Networks
Figure 9. Doubly-Terminated Topology
Page 6
to a maximum of 64 nodes per segment. The maximum to-
tal bus length and the maximum node−to−node length is
1640 ft. (500m) for Belden 8471 or NEMA Level 4. Maxi-
mum lengths are less for other smaller wire size cables.
Only one termination circuit module is required at any loca-
tion along the network. Refer to Echelon LonWorks
FTT−10 Transceiver User's Guide for additional details.
Free Topology Networks
Free topology segments require a termination circuit for
proper performance. Only one termination circuit module
is required at any location along the network (see figure 8).

Network Limits

(Doubly−Terminated Topology)
The LonWorks TP/FT−10 Doubly−Terminated topology
network is limited to a maximum of 64 nodes per segment.
The maximum total bus length is 5000 ft. (1524m) for Bel-
den 8471 or NEMA Level 4. Maximum bus lengths are less
for other smaller wire size cables.
The maximum stub length is 9.8 ft. (3m). In many cases
this bus network is connected in a daisy chain manner
where the bus is wired directly to each node, so stub length
is zero.
Two termination circuit modules (37X75) are required for
each segment. One must be located at each end of the net-
work (see figure 9).
STAR
TOPOLOGY
Termination
MIXED TOPOLOGY
(SINGLY TERMINATED)
Termination