Table 13: FC Bus rules for MS/TP devices
Category
Allowed maximums and rules
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.
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.
Table 14: SA Bus rules
Category
Allowed maximums and rules
General
Each bus supervisor supports one SA Bus.
Number of SA devices
SA Bus applications are limited to a power load of 240 mA. The best practice when configuring an
SA bus is to limit the total available operating power consumption to 100 mA or less.
Note:
Refer to the technical specifications on the type of sensors you are using as this limits
the amount of devices on the SA Bus.
365 m (1,198 ft) maximum bus length.
152 m (500 ft) maximum between an NS network sensor and the bus supervisor SNC supplying
power to the sensor) using bus cable connected to the SA Bus screw terminal blocks.
30 m (98 ft) maximum length for network sensors using bus cables connected to the 6-pin
modular jack (6-Pin SA Bus port).
Cable length for SA Bus
366 m (1,198 ft) maximum Bus Length.
Recommended bus cable type
Screw Terminal Connections
: 0.6 mm (22 AWG) Stranded 4-wire, 2-Twisted Pairs, Shielded Cable
for screw terminals.
Modular Jack Connections
: 6-Pin Modular Connectors with 24 or 26 AWG 6-Wire, 3 Twisted-Pairs.
EOL termination on the SA Bus
Each SA Bus supervisor has integral (fixed ON) EOL termination, which typically provides sufficient
EOL termination on a SA Bus. Long SA Bus runs or persistent communication problems on a SA
Bus may require EOL termination at the last device on the SA Bus in addition to the integral EOL
termination at the SA Bus supervisor) All SNC models are SA Bus supervisors.
SNC capabilities
Table 15: SNC capabilities
F4-SNC25151-0
F4-SNC25151-0x/x
F4-SNC16121-0
F4-SNC16121-04
Onboard I/O
25 inputs/15 outputs
25 inputs/15 outputs
16 inputs/12 outputs
16 inputs/12 outputs
Maximum objects in
device
2500
2500
2500
2500
Number of site devices
including self
1
1
1
1
Maximum allowed devices
across all integrations. For
example, MS/TP+IP.
96
4
60
4
Ethernet
2
2
2
2
BACnet/IP maximum
trunks
1
1
1
1
BACnet/IP maximum
devices per trunk
50
4
50
4
F4-SNC Installation Guide
21
