Table 8: Communications Bus and supply terminal blocks, functions, ratings, requirements, and cables
Terminal block/
port label
Terminal
labels
Function, electrical ratings/requirements
Recommended cable type
- (03)
+ (04)
SA Bus Communications
COM (02)
SA Bus Signal Reference and 15 VDC Common
SA BUS
SA PWR (01) 15 VDC Supply Power for Devices on the SA Bus (Maximum total
current draw for SA Bus is 240 mA.)
0.6 mm (22 AWG) stranded, 4-
wire twisted, shielded cable
recommended
Note:
The + and - wires are
one twisted pair and the COM
and SA PWR are the second
twisted pair of wires.
SA BUS
(Port)
6-Position Modular Connector provides:
•
SA Bus Communications
•
SA Bus Signal References and 15 VDC Common
•
15 VDC Power for devices on the SA Bus and
•
Wireless Commissioning Converter
24 AWG 3-pair CAT 3 Cable <30.5 m
(100 ft)
HOT
24 VAC Power Supply - Hot
Supplies 20-30 VAC (Normal 24 VAC)
24~
COM
24 VAC Power Supply Common
(Isolated from all other
Common terminals on controller)
0.8 mm to 1.5 mm (20 to 16 AWG) 2-
wire
Note:
• See Table 7 to determine wire size and cable
lengths for cables other than the recommended
cables.
FC Bus and SA Bus and supply power
wiring guidelines
Table 8 provides information about the functions, ratings,
and requirements for the SNC communication bus
and supply power terminals, and guidelines for wire
sizes, cable types, and cable lengths when wiring the
communication buses and supply power.
In addition to the guidelines in Table 8, observe these
guidelines when wiring the FC Bus and SA Bus supply
power:
• Run all low-voltage wiring and cables separate from
high-voltage wiring.
• Use twisted, insulated, stranded copper wire for all FC
and SA Bus cables, regardless of wire size.
• Shielded cable is strongly recommended for all FC and
SA Bus cables.
Termination diagrams
A set of Johnson Controls termination diagrams provides
details for wiring inputs and outputs to the controllers.
See the figures in this section for the applicable
termination diagrams.
F4-SNC Installation Guide
12
