I/O Terminal blocks, ratings, and
requirements
Table 2: I/O terminal blocks, functions, ratings, requirements, and cables
Terminal block label Terminal
label
Function, ratings, requirements
Determine wire size and
maximum cable length
+15 V
15 VDC Power Source
for active (3-wire) input devices
connected to the Universal IN
n
terminals.
Provides 100 mA total current
Same as (Universal)
IN
n
Note:
Use 3-wire cable for
devices that source power
from the +15 V terminal.
Analog Input - Voltage Mode (0–10 VDC)
10 VDC maximum input voltage
Internal 75k ohm Pull-down
See Guideline
A
Analog Input - Current Mode (4–20 mA)
Internal 100 ohm load impedance
Note:
A current loop fail-safe jumper can be positioned
to maintain a closed 4 to 20 mA current loop, even when
the power to the expansion module is interrupted or off.
See Guideline
B
in Table 3.
Analog Input - Resistive Mode (0–600k ohm)
Internal 12 V. 15k ohm pull up
Qualified Sensors: 0-2k ohm 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, 2.252k Type II)
See Guideline
A
IN
n
Binary Input - Dry Contact Maintained Mode
1 second minimum pulse width
Internal 12 V. 15k ohm pull up
See Guideline
A
UNIVERSAL
(Inputs)
ICOM
n
Universal Input Common
for all Universal Input terminals
Same as (Universal)
IN
n
Analog Output - Voltage Mode (0–10 VDC)
10 VDC maximum output voltage
10 mA maximum output current
Required an external load of 1,000 ohm or more.
Note:
The Analog Output (AO) operates in the Voltage
Mode when connected to devices with impedances
greater than 1,000 ohm. Devices that drop below 1,000
ohm may not operate as intended for Voltage Mode
applications.
OUT
n
Analog Output - Current Mode (4–20 mA)
Requires an external load between 0 and 300 ohm.
Note:
The Analog Output (AO) operates in the Current
Mode when connected to devices with impedances less
than 300 ohm. Devices that exceed 300 ohm may not
operate as intended for Current Mode applications.
ANALOG
(Outputs)
OCOM
n
Analog Output Signal Common
for all Analog OUT terminals.
See Guideline
C
in Table 3.
IOM2721 Input/Output Module Installation Guide
6