Omega Products OM7-21 User Manual

H-33

The OM7 Series modular isolation-based, single­channel plug-in signal conditioning system accepts
inputs from a wide range of process control transducers
and signals while providing high-level output voltages.
Featuring a maximum nonlinearity of 0.02% and factory
calibrated to guarantee maximum accuracy of ±0.1%,
the OM7 Series offers superior performance at a lower
cost than multipurpose signal conditioners. The
modules provide 1500 V rms isolation and 120 V rms
of field wiring input protection. The power supplies
necessary to drive each individual module’s input
circuitry are internally isolated, enabling the OM7
modules to offer true channel-to-channel isolation
of the input signals. The modules are rated for a
nominal power supply input of 24 Vdc and, for
maximum flexibility, will accept supply voltages in the
14 Vdc to 35 Vdc range.

All modules are packaged in a compact 54 x 42 x
14 mm (2.1 x 1.7 x 0.6") durable plastic case that
readily accommodates high channel density
applications. Each module may be operated in high
humidity (noncondensing) environments and is rated
over the extended -40 to 85°C industrial temperature
range. All modules feature a simple pinout that allows

OM7 Series Modular
Signal Conditioning System

Accepts a Wide Range of Inputs

⻬ Isolated Signal Conditioners for a

Wide Range of Process Control Signals:
Thermocouples, RTDs, mA, mV, V

⻬ Process Current (4-20 and 0-20 mA)

Output Module

⻬ Powered mA Input Module Includes

Isolated 24 Vdc Power for a Remote
Transmitter

⻬ Bipolar Voltage Input and Output

Modules

⻬ Operates From a Single 24 Vdc

Power Supply

⻬ Provides 1-5 V, 0-10 V, and

±10 V Output Options

⻬ ±0.1% Max. Accuracy, Factory Calibrated
⻬ 1500 V rms of CMV Isolation and

120 V rms Field Wiring Protection

⻬ Compact, 54 x 42 x 14 mm

(2.1 x 1.7 x 0.6" ) Plastic Housing

Extended Warranty

Program

SM

A/IN

A/OUT

H

them to be mixed and matched within a single
backplane design. Furthermore, modules are easily
serviced since they can be removed and inserted into
the backplane with power applied.

Modules are available to isolate and condition the
following input signals and transducers: voltage,
process current, RTD, 2-wire transmitter, and
thermocouples. The 2-wire transmitter interface module
(OM7-35) accepts a 4-20 mA process input and
provides an isolated 24 Vdc supply to power the
current loop. In this way, a loop-powered transmitter
can be directly connected to the OM7-35 without
requiring a separate power supply. All of the isolated
input modules, with the exception of the OM7-21,
provide a high-level output voltage that is factory
configured for either the 1-5 V or 0-10 V range. The
OM7-21 is a unity gain, isolated input module with an
input/output range of ±10 V.

Modules are also available that provide isolated output
signals for process current and bipolar voltage.
The OM7-39 process current module converts either a
1-5 V signal to a 4-20 mA output or a 0-10 V input to a
0-20 mA output. The input/output ranges of the OM7­39 are factory configured. The OM7-22 is a unity gain
module that provides an isolated ±10 V output signal.

A full line of backplanes and rack-mount hardware
complete the OM7 Series signal conditioning system.
Each backplane contains screw terminals for field
wiring connections and a miniature cold junction
compensation (CJC) thermistor that is installed under
the terminal blocks of each channel. Due to the pinout
of the OM7 Series modules, the CJC thermistor affects
only the thermocouple modules. This flexibility permits
any module type to be used in any channel on the
backplane.

H-34

KMTSS-125G-6 thermocouple

probe sold separately, $24.

OM7 Series

$

103

Module Starting Price

Shown smaller than actual size.

Extended Warranty

Program

SM

A/IN

A/OUT

H-35

ISOLATED VOLTAGE
AND CURRENT INPUT

The OM7 Series feature five
isolated voltage/current input
modules capable of addressing
a wide variety of input voltage
ranges and signal dynamics.
The OM7-21 is a bipolar unit
module featuring a full-scale
range of ±10 V. The OM7-30 and
OM7-31 accept dc input voltages
and provide either a factory
configured 1-5 V or 0-10 V output
signal. The OM7-32 accepts a
4-20 mA process current input
signal and provides an output
voltage signal in the 1-5 V range.
The OM7-33 isolates a 1-5 V input
signal and provides a buffered
1-5 V output signal. The OM7-32
and OM7-33 can also be factory
configured to provide a 0-10 V
output signal with a 0-20 mA
or 0-5 V input, respectively.
Both the OM7-32 and OM7-33
have bandwidths of 100 Hz. The
OM7-30 and OM7-31 are limited
to 3 Hz bandwidth.

ISOLATED
THERMOCOUPLE INPUT

The OM7-37 and OM7-47 modules
accept inputs from types J, K, T, E,
R, S, and B thermocouples and
provide a 1-5 V or 0-10 V output
signal. The OM7-47 also accepts
inputs from type N thermocouples.
Both the OM7-37 and OM7-47 have
a nominal 3 dB bandwidth of 3 Hz,
and they provide for upscale open
input detection within 10 sec.

In addition to the signal conditioning
capabilities of the OM7-37, the
OM7-47 includes an

internallinearization circuit that
compensates for the inherent
nonlinearities of the thermocouple.
With this linearizer, the OM7-47 is
able to provide an output voltage
that is linear with respect to the
actual temperatures being
measured by the thermocouple.

The thermocouple input modules
accomplish CJC by means of an
external thermistor mounted under
the field wiring screw terminal
blocks of the backplane.

ISOLATED LINEARIZED
RTD INPUT

The OM7-34 module accepts inputs
from 100Ω platinum and 120Ω

nickel RTDs and produce an output
voltage signal that is proportional
with temperature measured by the
RTD. The OM7-34 modules are
available in a factory-configured
1-5 V or 0-10 V output range.
Three-wire lead resistance
compensation is provided and
2- or 3-wire RTDs may be used.
The OM7-34 RTD input module has
a nominal 3 dB bandwidth of 3 Hz
and upscale open
RTD detection with 10 sec.

ISOLATED 2-WIRE
TRANSMITTER INTERFACE

The OM7-35 input module accepts
a 4-20 mA process current input,
provides a standard 1-5 V output
signal, and features an isolated
loop power supply for driving the
current transmitter.

Modular Signal
Conditioning System