neywell Inc. All Rights Reserved

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®
Bus
Wiring Guidelines
INTRODUCTION
The Free Topology Transceiver (FTT) supports polarity
insensitive, free topology wiring. This frees the system
installer from wiring using a specific bus topology. T-tap, star,
loop, and mixed wiring topologies are all supported by this
architecture. Free topology wiring reduces the time and
expense of system installation by allowing the wiring to be
installed in the most expeditious manner. It also simplifies
network expansion by eliminating restrictions on wire routing,
splicing, and device placement.
A FTT network can be comprised of multiple segments
(L
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Bus sections containing from one to sixty
devices, each device having a Neuron® ID to validate)
separated by physical layer repeaters or routers.
FTT networks are very flexible and convenient to install and
maintain, but it is imperative to carefully plan the network
layout and create and maintain accurate documentation. This
will aid in compliance verification and future expansion of the
FTT network. This will also minimize unknown or inaccurate
wire run lengths, node-to-node (device-to-device) distances,
node counts, total wire length, inaccurate repeater/router
locations, and misplaced or missing terminations.
APPLICATIONS
A free topology architecture allows the user to wire the control
devices with virtually no topology restrictions.
Unlike bus wiring designs, the FTT system uses a free
topology wiring scheme that supports T-tap, star, loop, mixed,
and/or daisy-chain (see Fig. 1). This design has many
advantages. First, the installer is free to select the method of
wiring that best suits the installation, reducing the need for
advanced planning and allowing last minute changes at the
installation site. Second, if installers have been trained to use
one style of wiring for all installations, free topology
technology can be introduced without requiring retraining.
Third, retrofit installations with existing wiring plans can be
accommodated with minimal, if any, rewiring. This capability
ensures that FTT technology can be adapted to both old and
new projects, widening the potential market for FTT based
products. Finally, free topology allows FTT systems easy
future expansion by tapping into the existing wiring where it is
most convenient to do so. This reduces the time and expense
of system expansion, and from the customers perspective,
keeps down the life cycle cost of the free topology network.
Fig. 1. Typical wiring topologies
supported by the FTT System.
TERMINATION
MODULE
TERMINATION
MODULE
DEVICE
DEVICE
DEVICE
TERMINATION
MODULE
TERMINATION
MODULE
DEVICE
DEVICE
DEVICE
MIXED
LOOP
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
SINGLY TERMINATED
STAR
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
M12197 L
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BUS WIRING GUIDELINES
74-28652
2
System expansion is simplified by the use of physical layer
repeaters and routers. The Q7740A 2-Way or Q7740B 4-Way
Devices perform a repeater function, and the Q7751A
operates as a router. See Fig. 2. If a L
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Bus segment
grows beyond the maximum number of devices or total wire
distance, then additional FTT segments can be added. This is
done by connecting a Q7740A 2-Way or a Q7740B 4-Way
physical layer repeater (see Fig. 3). The repeaters will transfer
data between the two L
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Bus segments, this allows
the number of devices to be spread out as well as increasing
the length of wire over which they communicate.
NOTE:
Do not exceed the maximum of 120 devices for a
Q7750A Zone Managers L
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Bus network
(up to 60 devices are allowed per L
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Bus
segment).
The repeater function permits an FTT network to grow as
system needs expand, without retrofitting existing controllers
or requiring the use of specialized bridges. The maximum
number of repeaters per L
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Bus segment is one
(on either side of the router). A Q7751A L
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Bus
Router can also be used to effectively double the maximum
L
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Bus length. The advantage of using the router is
that it will segregate traffic to an L
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Bus segment,
when using the repeater all traffic is repeated on each
L
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Bus segment. (see following NOTES).
NOTES: There can be no more than one repeater on either
side of a Q7751A Router.
An FTT network can have no more than one router
per Zone Manager. Systems requiring high levels of
network traffic may benefit from the use of a Q7751A
Router which forwards packets only when necessary.
Routers are not allowed within loops.
Fig. 2. Repeaters and Router in a FTT network.
Fig. 3. Physical Layer Repeater (Q7740A 2-Way or Q7750B 4-Way).
NETWORK CABLING AND
CONNECTIONS
This section provides information about cabling and FTT
network connections.
IMPORTANT
For network terminal connections, twist the wires
together a minimum of three times.
Only use approved wire and do not use different wire
types on the same bus.
Follow the bus length limits for the cable type used.
Properly install the 209541B FTT Termination
Module, see Fig. 4 through 7.
System Performance and Cable Selection
Transmission Specifications
The free topology transmission specifications includes two
rules which must both be met for proper system operation:
1.
The distance from each device to all other devices and
to the termination must not exceed the (singly
terminated) maximum node-to-node (device-to-device)
distance. For example, if multiple paths exist, using loop
topology, then the longest path should be used for the
calculations.
2.
The maximum total wire length is the total amount of
wire connected per L
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Bus segment.
See Table 1 for daisy-chain doubly terminated FTT network
bus topology transmission specifications including Echelon®
cable parameters.
209541B
TERMINATION
MODULE
209541B
TERMINATION
MODULE
209541B
TERMINATION
MODULE
Q7740A
REPEATER
Q7740A
REPEATER
Q7751A2002
ROUTER
DAISY-CHAIN
TOPOLOGY
DAISY-CHAIN
TOPOLOGY
DAISY-CHAIN
TOPOLOGY
DAISY-CHAIN
TOPOLOGY
209541B
TERMINATION
MODULE
M12369A
Q7740B
4-WAY
REPEATER
209541B
TERMINATION
MODULE
DAISY-CHAIN
TOPOLOGY
FREE
TOPOLOGY
FREE
TOPOLOGY
FREE
TOPOLOGY
M12368
Q7740A
2-WAY
REPEATER
FREE
TOPOLOGY
FREE
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BUS WIRING GUIDELINES
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74-28652
Table 1. Daisy-chain FTT Network Bus Topology Transmission Specifications (Doubly Terminated).
See Table 2 for singly terminated FTT network bus topology
transmission specifications.
Table 2. FTT Network Free Topology Transmission Specifications (Singly Terminated).
See Table 3 and 4 for a list of Honeywell provided FTT
daisy-chain and free topology network wire/cables.
Table 3. Honeywell Provided Daisy-Chain (Doubly Terminated) FTT Network Wire/Cables.
Table 4. Honeywell Provided Free Topology (Singly Terminated) FTT Network Wire/Cables.
See the generic cable manufacturer information that meets
Echelon L
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Bus specifications in Table 5.
Wire/Cable type (Unshielded)
Maximum FTT network bus length
for segment(s) in feet (meters)
Cable Parameters
AWG/Dia. RloopW/km C nF/km
Vprop% of c
Belden 85102 (stranded non-
plenum)
8900 (2700)
16/1.5mm
2
28
56
62
Belden 8471 (stranded non-
plenum)
8900 (2700)
16/1.5mm
2
28
72
55
Level IV Cable Specifications,
22AWG (solid/stranded twisted pair)
4600 (1400)
22/.34mm
2
106
49
67
TIA568A Category 5 24 AWG
(twisted pair solid or stranded,
plenum or non-plenum)
3000 (900)
24/.27mm
2
168
46
58
Wire/Cable type (Unshielded)
Maximum FTT network bus length
for segment(s) in feet (meters)
Maximum node-to-node length
for segment(s) in feet (meters)
Belden 85102 (stranded non-plenum)
1640 (500)
1640 (500)
Belden 8471 (stranded non-plenum)
1640 (500)
1300 (400)
Level IV Cable Specifications, 22AWG
(solid/stranded twisted pair)
1640 (500)
1300 (400)
TIA568A Category 5 24 AWG twisted pair (solid
or stranded, plenum or non-plenum)
1500 (450)
820 (250)
Wire/Cable type (Solid Unshielded)
Maximum FTT network bus length for segment(s) in feet (meters)
AK3791 - plenum (one twisted pair)
4600 (1400)
AK3792 - plenum (two twisted pair)
AK3781 - non-plenum (one twisted pair)
AK3782 - non-plenum (two twisted pair)
Wire/Cable type (Solid Unshielded)
Maximum FTT network bus length
for segment(s) in feet (meters)
Maximum node-to-node length
for segment(s) in feet (meters)
AK3791 - plenum (one twisted pair)
1640 (500)
1300 (400)
AK3792 - plenum (two twisted pair)
AK3781 - non-plenum (one twisted pair)
AK3782 - non-plenum (two twisted pair) Home and Building Control
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Honeywell Inc.
Honeywell Limited-Honeywell Limitée
Honeywell AG
Honeywell Plaza
155 Gordon Baker Road
Böblinger Straße 17
P.O. Box 524
North York Ontario
D-71101 Schönaich
Minneapolis, MN 55408-0524
M2H 3N7
Phone (49-7031) 637-01
Fax (49-7031) 637-493
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paper containing at least 10%
post-consumer paper fibers.
L
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BUS WIRING GUIDELINES
74-28652 J.D. Rev. 9-99
www.honeywell.com
Table 5. Echelon Generic Cable Specification For Belden 85102 Equivalent, Stranded Twisted Pair 16 AWG (1.5mm
2
).
Cable Termination
The FTT network segment requires termination for proper
data transmission performance. Use a 209541B FTT
Termination Module. Free Topology (singly terminated)
segments use the yellow and brown wires. Daisy-chain
(doubly terminated) segments use the orange and brown
wires. See Fig. 4.
Fig. 4. 209541B FTT Termination Module.
Free Topology (Single Termination)
Network Segment
In a free topology s