Johnson Controls IOM3721 Installation Manual page 8

Table 3: Communications bus and supply power terminal blocks, functions, ratings, requirements, and
cables
Terminal block/Port
Terminal labels Function, electrical ratings/Requirements
label
HOT
24~
COM
Note: See Table 2 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 at 38,400 baud. For more information,
refer to the MS/TP Communications Bus Technical
Bulletin (LIT-12011034).
Terminal Wiring Guidelines,
Functions, Ratings, and
Requirements
Input and Output wiring guidelines
Table 4 provides information and guidelines about
the functions, ratings, and requirements for the
expansion module input and output terminals, and
references guidelines for determining proper wire
sizes and cable lengths.
In addition to the wiring guidelines in Table 4
• Run all low-voltage wiring and cables separate
from high-voltage wiring.
• All input and output cables, regardless of wire
size or number of wires, should consist of
stranded, insulated, and twisted copper wires.,
observe these guidelines when wiring controller
inputs and outputs:
• Shielded cable is not required for input or output
cables.
• Shielded cable is recommended for input
and output cables that are exposed to high
electromagnetic or radio frequency noise.
• Inputs/outputs with cables less than 30 m (100 ft)
typically do not require an offset in the software
setup. Cable runs over 30 m (100 ft) may require
an offset in the input/output software setup.
8 IOM3721 Expansion Input/Output Module Installation Guide
24 VAC Power Supply - Hot
Supplies 20–30 VAC (Nominal 24 VAC)
24 VAC Power Supply - Common
Recommended cable type
0.8 mm to 1.0 mm
(18 AWG) 2-wire