VMA Terminal Functions, Ratings,
Requirements, and Wiring Guidelines
Input and Output Wiring Guidelines
Table 1
provides information about the functions, ratings,
and requirements for the VMA input and output terminals;
and references guidelines for determining proper wire
sizes and cable lengths.
In addition to the wiring guidelines in
Table 1
, observe
these guidelines when wiring VMA inputs and outputs:
•
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 twisted, insulated,
and stranded copper wires.
•
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.
•
Cable runs that are less than 30 m (100 ft) typically
do not require an offset in the input/output software
setup. Cable runs that are over 30 m (100 ft) may
require an offset in the input/output software setup.
Table 1: I/O Terminal Blocks, Functions, Ratings, Requirements, and Cables
To Determine Wire Size and
Maximum Cable Length
Function, Ratings, and Requirements
Terminal
Labels
Terminal Block
Label
Same as (Universal)
INn
.
Note:
Use 3-wire cable for
devices that source power from
the +15 V terminal.
15 VDC Power Source
for active (3-wire) input devices
connected to the Universal IN
n
terminals.
Provides 100 mA total current.
+15 V
UNIVERSAL
(Inputs)
See Guideline A in
Table 2
.
Analog Input - Voltage Mode (0–10 VDC)
10 VDC maximum input voltage
Internal 75k ohm Pulldown
INn
See Guideline A in
Table 2
.
Analog Input - Resistive Mode (0–600k ohm)
Internal 12 V, 15k ohm pull up
Qualified Sensors: 0–2k potentiometer,
RTD (1k Nickel [Johnson Controls sensor],
1k Platinum, and A99B Silicon Temperature Sensor)
Negative Temperature Coefficient (NTC) Sensor
10K Type L (10K JCI Type II is equivalent to Type L) or
2.252K Type II
Same as (Universal)
INn
.
Universal Input Common
for all Universal IN terminals
Note:
All Universal ICOM
n
terminals share a common,
which is isolated from all other commons.
ICOMn
7
VMA1610 and VMA1620 Variable Air Volume Controllers Installation Instructions
