Max wire length by current and wire size
graphic
Figure 8: Maximum wire length for low-voltage (<30
V) Inputs and Outputs by current and wire size
Communications bus and supply
power wiring guidelines
Table 5 provides information about the functions, ratings,
and requirements for the communication bus and supply
power terminals; and guidelines for wire sizes, cable
types, and cable lengths when wiring the controller's
communication buses and supply power.
In addition to the guidelines in Table 5, observe these
guidelines when wiring an SA or FC bus and the 24 VAC
supply power:
• Run all low-voltage wiring and cables separate from
high-voltage wiring.
• 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
MS/TP Communications Bus Technical
Bulletin (LIT-12011034)
for detailed information
regarding wire size and cable length requirements for
the SA and FC buses.
Comm bus and supply power terminal
blocks rating and requirements
Note:
The SA Bus and FC 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)
.
Table 5: Communications bus and supply power terminal blocks, functions, ratings, requirements, and cables
Terminal block/
Port label
Terminal
labels
Function, electrical ratings/Requirements
Recommended cable type
+
-
FC Bus Communications
COM
Signal Reference (Common) for Bus communications
FC BUS
SHLD
Isolated terminal (optional shield drain connection)
0.6 mm (22 AWG) stranded, 3-wire
twisted, shielded cable recommended
FC BUS
(Port)
FC Bus
RJ-12 6-Position Modular Connector provides:
FC Bus Communications
FC Bus Signal Reference and 15 VDC Common
15 VDC, 180 mA, Power for Wireless Commissioning Converter
or ZFR181x/ZFR182x Wireless Router
Wireless Commissioning Converter
retractable cable or 24 AWG 3-pair
CAT 3 Cable <30.5 m (100 ft)
+
-
SA Bus Communications
COM
SA Bus Signal Reference and 15 VDC Common
SA BUS
SA PWR
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
(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.
Sensor
Sensor
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 Wireless
Commissioning Converter
24 AWG 3-pair CAT3 cable <30.5 m
(100 ft)
HOT
24 VAC Power Supply - Hot
Supplies 20–30 VAC (Nominal 24 VAC)
24~
COM
24 VAC Power Supply Common
(Isolated from all other
Common terminals on controller)
35 VA
0.8 mm to 1.0 mm
(18 AWG) 2-wire
FEC26 Field Equipment Controllers Installation Guide
11
