Johnson Controls F4-XPM Series Installation Manual page 8

Communications bus and supply power
wiring guidelines
Table 4 provides information about the functions, ratings,
and requirements for the communication bus and supply
power terminals. The table also provides guidelines for
wire sizes, cable types, and cable lengths for wiring the
expansion module's communication bus and supply
power.
In addition to the guidelines in Table 4, observe the
following guidelines when wiring an FC bus, SA bus, or the
24 VAC supply power:
• Run all low-voltage wiring and cables separate from
high-voltage wiring.
Table 4: Communications bus and supply power terminal block functions, ratings, requirements, and cable
guidelines
Terminal block/ Terminal
Port label labels
+
-
COM
FC BUS
or
SHD
SA BUS
or
PWR
SA/FC BUS
(Port)
HOT
24V~
COM
Note: See Table 1 to determine wire size and cable
lengths for cables.
Note: The SA Bus and FC Bus wiring
recommendations in this table are for MS/TP
bus communications at 38,400 baud. For more
information, refer to the FX-PC Series Controllers
MS/TP Communications Bus Technical Bulletin
(LIT-12011670)..
8 F4-XPM Expansion Modules Installation Guide
Function, electrical ratings/Requirements
FC or SA Bus Communications
Signal Reference (Common) for FC or SA Bus
communications
SHD on FC Bus: Isolated terminal (optional shield drain
connection
PWR on SA Bus: 15 VDC power lead connection.
(Maximum total current draw for SA bus is 240 mA.)
RJ-12 6-Position Modular Connector provides:
• FC or SA Bus Communications
• FC or SA Bus Signal Reference and 15 VDC
Common
24 VAC Power Supply - Hot
Supplies 20–30 VAC (Nominal 24 VAC)
24 VAC Power Supply - Common
(Isolated from all other Common terminals on
controller.)
• All SA and FC bus cables, regardless of wire size, should
be twisted, insulated, stranded copper wire.
• Shielded cable is strongly recommended for all SA and
FC bus cables.
• Refer to the FX-PC Series Controllers MS/TP
Communications Bus Technical Bulletin (LIT-12011670)
for detailed information regarding wire size and cable
length requirements for SA buses.
Recommended cable type
FC Bus: 0.6 mm (22 AWG) stranded,
3-wire twisted, shielded cable
recommended.
SA Bus: 0.6 mm (22 AWG) stranded, 4-
wire (2 twisted-pairs), shielded cable
recommended.
24 AWG 3-pair CAT 3 Cable <30.5 m (100
ft)
0.8 mm to 1.0 mm
(18 AWG) 2-wire
Note: On the SA Bus, the + and
- wire are one twisted pair, and
the COM and PWR are the second
twisted pair of wires.