Communications Bus And Supply Power Wiring Guidelines - Johnson Controls ATC1510 Installation Manual

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 controller's communication buses and supply power.
In addition to the guidelines in Table 4, observe the following guidelines when you wire an FC or SA bus and the 24
VAC supply power:
• Run all low-voltage wiring and cables separate from high-voltage wiring.
• All FC and SA bus cables, regardless of wire size, should be twisted, insulated, stranded copper wire.
• Using shielded cable is best practice for all FC and SA bus cables.
• Refer to the MS/TP Communications Bus Technical Bulletin (LIT-12011034) for detailed information regarding wire
size and cable length requirements for FC and SA buses.
Table 4: Communications bus and supply power terminal blocks, functions, ratings, requirements, and
cables
Terminal block/ Terminal
Port label labels
+
-
2
FC BUS
COM
SHIELD
+
-
COM
SA BUS 2
PWR
SA BUS (Port) 2
SA BUS
LINE
240VAC, 20VA
NEUTRAL
1 See Input and Output wiring guidelines
2 The FC bus and SA bus wiring recommendations in this table are for MS/TP Bus communications at 38.4k baud. For more
information, refer to the MS/TP Communications Bus Technical Bulletin (LIT-12011034).
8 ATC1510 Advanced Terminal Unit Controller Installation Guide
Function, electrical ratings/Requirements
FC Bus Communications
Signal Reference (Common) for Bus communications
Isolated terminal (optional shield drain connection)
SA Bus Communications
SA Bus Signal Reference and 15 VDC Common
15 VDC Supply Power for Devices on the SA Bus
(Maximum total current draw for the SA Bus is 210 mA.)
RJ-12 6-Position Modular Connector provides:
SA Bus Communications
SA Bus Signal Reference and 15 VDC Common
15 VDC Power for devices on the SA bus and BTCVT or MAP
Gateway
240 VAC Power Supply - Line
Supplies 240 VAC (50/60 Hz)
240 VAC Power Supply - Neutral
to determine wire size and cable lengths for cables other than the recommended cables.
Recommended cable type
2
0.5 mm (22 AWG) stranded, 3-wire
twisted, shielded cable recommended
2
0.5 mm (22 AWG) stranded, 4-wire
(2 twisted-pairs), shielded cable
recommended.
Note: The + and - wire
are one twisted pair, and
the COM and SA PWR are
the second twisted pair of
wires.
24 AWG 3-pair CAT3 cable <30.5 m
(100 ft)
2
1.0 mm
(18 AWG) 2-wire
1