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EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER
17 74-2958—1
Fig. 8. DIN rail adapters.
The FTT supports polarit
y
insensitive free topolo
gy
wirin
g
.
This frees the s
y
stem installer from wirin
g
usin
g
a specific bus
topolo
gy
. T-tap, star, loop, and mixed wirin
g
topolo
g
ies are all
supported b
y
this architecture. The maximum L
ON
W
ORKS
Bus
len
g
th when usin
g
a combination of T-tap, star, loop, and bus
wirin
g
(
sin
g
l
y
terminated
)
is 1640 ft.
(
500m
)
with the maximum
node-to-node len
g
th of 1312 ft.
(
400m
)
. In the event that the
total wire len
g
th is exceeded, then a Q7740A 2-Wa
y
Repeater
or a Q7740B 4-Wa
y
Repeater can be used to allow the
number of devices to be spread out as well as increasin
g
the
len
g
th of wire over which the
y
communicate. The maximum
number of repeaters per se
g
ment is one
(
on either side of the
router
)
. A Q7751A,B L
ON
W
ORKS
Bus Router can also be used
to effectivel
y
double the maximum L
ON
W
ORKS
Bus len
g
th.
The advanta
g
e of usin
g
the router is that it se
g
re
g
ates traffic
to a se
g
ment while when usin
g
the repeater, all traffic is
repeated on each se
g
ment. When utilizin
g
a doubl
y
terminated L
ON
W
ORKS
Bus structure, use a continuous dais
y
-
chain with no stubs or taps from the main backbone, The
maximum L
ON
W
ORKS
Bus len
g
th is 4593 ft.
(
1400m
)
with the
maximum node-to-node len
g
th of 3773 ft.
(
1150m
)
.
FTT networks are ver
y
flexible and convenient to install and
maintain, but it is imperative to carefull
y
plan the network
la
y
out and create and maintain accurate documentation. This
aids in compliance verification and future expansion of the
FTT network. This also keeps unknown or inaccurate wire run
len
g
ths, node-to-node
(
device-to-device
)
distances, node
counts, total wire len
g
th, inaccurate repeater/router locations,
and misplaced or missin
g
terminations minimized. Refer to
L
ON
W
ORKS
Bus Wirin
g
Guidelines form, 74-2865 for complete
description of network topolo
gy
rules.
L
ON
M
ARK
® FUNCTIONAL PROFILE
W7750 Controllers support the L
ON
M
ARK
Functional Profile
number 8030 Roof Top Unit Controller, version 1.0
(
see Fi
g
. 9
)
.
M6857
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