DISTRIBUTED I/O
EN0B-0090
22
Table 11. Doubly-terminated bus specifications.
Cable Type
Max. bus length
Belden 85102
8,900 ft (2,700m)
Belden 8471
8,900 ft (2,700m)
Level IV, 22 AWG
4,600 ft (1,400m)
JY (St) Y 2x2x0.8
3,000 ft (900m)
TIA568A Categ. 5 24AWG, twisted pair
3,000 ft (900m)
NOTE:
The cable types listed above are as recommended
by Echelon® in their FTT-10A User Guide. The
cable recommended by Honeywell is the level IV, 22
AWG, solid core, nonshielded cable. Belden part
numbers are 9H2201504 (plenum) and 9D220150
(non-plenum).
TERMINATION
MODULE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
TERMINATION
MODULE
Figure 29. Doubly-terminated bus configuration
(recommended).
Free topology requires only one bus termination and allows a
variety of bus configurations (see Figure 30):
TERMINATION
MODULE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
SINGLY TERMINATED
DEVICE
DEVICE
TERMINATION
MODULE
DEVICE
DEVICE
STAR
Figure 30. Possible bus configurations
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
TERMINATION
MODULE
DEVICE
DEVICE
DEVICE
MIXED
TERMINATION
MODULE
DEVICE
DEVICE
DEVICE
DEVICE
DEVICE
LOOP
Figure 31. Free topology examples.
The FTT specification includes two components that must be
met for proper system operation. The distance from each
transceiver to all other transceivers and to the termination
must not exceed the
maximum node-to-node distance
. If
multiple paths exist, the
maximum total wire length
is the total
amount of wire used.
Table 12. Free topology (singly-terminated)
specifications.
Cable type
Maximum node-
to-node distance
Maximum total
wire length
Belden 85102
1,650 ft (500m)
1,650 ft (500m)
Belden 8471
1,300 ft (400m)
1,650 ft (500m)
Level IV, 22AWG
1,300 ft (400m)
1,650 ft (500m)
JY (St) Y 2x2x0.8
1,050 ft (320m)
1,650 ft (500m)
TIA568A Category 5
24AWG, twisted pair
825 ft (250m)
1,500 ft (450m)
IMPORTANT
Do not use different wire types or gauges on the
same L
ON
W
ORKS
network segment. The step
change in line impedance characteristics would
cause unpredictable reflections on the bus.
