Table 3: FC Bus rules
Category
Rules/maximums allowed
General
One FC Bus with up to 32 MS/TP devices (on NCE256x models only).
Note:
An FC port on a network engine can connect to only one
bus segment on an FC Bus.
Only a daisy-chain topology is allowed (no T or Star topology
configurations).
Number of devices
One FC Bus Supports up to 32 MS/TP controllers on a single FC Bus
segment.
FC Bus can be up to 1,520 m (4,987 ft) using 0.6 mm (22 AWG) 3-wire
twisted, shielded cable.
Cable length for FC bus
When using fiber-optic connections: 2,010 m (6,594 ft) between two
fiber-optic modems.
Cable
Stranded 0.6 mm (22 AWG) 3-wire twisted, shielded cable is
recommended.
Stranded 0.6 mm (22 AWG) 4-wire (two twisted-pairs) shielded cable
is acceptable.
Note:
Ensure the + and - bus leads are a twisted pair. On
applications using 4-wire (two twisted-pairs) cable, isolate and
insulate unused conductor. Refer to the
MS/TP Communications
Bus Technical Bulletin (LIT-12011034)
for more information.
EOL termination on the FC
bus
The EOL switch must be set to
On
(or an EOL terminator installed)
on the two devices located at either end of each bus segment on
an FC Bus. The EOL switches must be set to
Off
(or EOL termination
disabled) for all other devices on the bus segment on an FC Bus. See
Setting the end-of-line switch
for information on setting the EOL
switch.
SA Bus rules
The SA Bus connects the
Metasys
Input/Output Modules (IOMs), NS Series Network Sensors,
DIS1710 Local Controller Display, specified variable frequency drives, and Wireless Commissioning
Converter (MS-BTCVT-1) to an NCE.
Observe the rules in the following table when designing and installing the SA Bus for your
application.
Table 4: SA Bus rules
Category
Rules/limits
General
Each bus supervisor supports one SA Bus.
The SA Bus supports up to 10 devices.
Note:
The SA Bus supervisor provides power for the NS
network sensors on the bus. Due to power limitations, only 4
of the 10 devices on a SA Bus can be NS sensors. The SA Bus on
NCE25 models that have an integral Local Controller Display do
not support an optional DIS1710 Local Controller Display.
Number of devices
supported on the bus
The SA Bus does not support repeaters.
9
NCE25 Installation Instructions