DISTRIBUTED I/O
23 EN0B-0090GE51 R0802
device
device
termination
module
CPU
device
termination
module
device
device
device
100 m
(328 ft.)
100 m
(328 ft.)
100 m (328 ft.)
100 m (328 ft.)
100 m
(328 ft.)
200 m
(656 ft.)
200 m
(656 ft.)
ALLOWED:
node-to-node = 200 m (656 ft.)
total wire length = 400 m (1312 ft.)
NOT ALLOWED:
node-to-node = 400 m (1312 ft.)
total wire length = 500 m (1640 ft.)
NOT ALLOWED:
node-to-node = 200 m (656 ft.)
total wire length = 600 m (1968 ft.)
termination
module
device
device
device
device
device
100 m
(328 ft.)
100 m
(328 ft.)
200 m
(656 ft.)
Fig. 32. Example of allowed/not-allowed free topology
layouts (max. node-to-node distance: 320 m, max. wire
length: 500 m)
NOTE: In the event that the limit on the total wire length is
exceeded, then FTT physical layer repeaters
(FTT 10A) can be added to interconnect segments
and increase the overall length by an amount equal
to the original specification for that cable type and
bus type for each repeater used. For example,
adding repeaters for a doubly-terminated bus using
JY (St) Y 2x2x0.8 cable increases the maximum
length 3000 ft (900m) for each repeater.
LONWORKS Bus Termination Modules
Depending upon the configuration, either one or two
termination modules are required for terminating a
L
ONWORKS bus with FTT devices on it. The following two
different L
ONWORKS termination units are available for this
purpose:
• 209541B L
ONWORKS Bus Termination Module (see Fig.
33 and Fig. 34) and
• XAL-Term L
ONWORKS connection and termination
module (see Fig. 35), which can be mounted on DIN rails
and in fuse boxes.
Fig. 33. Termination Module 209541B connections for
doubly-terminated FTT network
Fig. 34. Termination Module 209541B connections for a
singly-terminated FTT network
3
4
L
O
N
Ho
n
e
y
w
e
l
l
X
A
L
-
T
e
r
m
L
O
N
removable screw-type
3-pole terminal block
1
5
34
06
shield shield
LON
Termin ation
FTT/LPT Bus
FTT/LPT Free
Park Position
plug-in
jumper
Fig. 35. XAL-Term
In the case of either a daisy chain or free-topology
L
ONWORKS bus layout, the maximum lengths described
above must be adhered to.
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