Analog Devices B32 0 (4) Datasheet

Isolated, Process Current Input

FEATURES

Interfaces, amplifies, & filters a process-current input.
Process-current input signals are measured by reading the
voltage across an external precision 100Ω resistor (supplied

with module).
Module provides simultaneous precision voltage and

current outputs.
Module circuitry can withstand 220v rms at the input screw-

terminals.
All 3B32 series modules are mix-and-match and Hot

Swappable.

APPLICATIONS

Industrial signal conditioning
Industrial signal isolation
Industrial signal filtering

PRODUCT OVERVIEW

The 3B Series of Signal Conditioning I/o Subsystems provide a
low-cost, versatile method of transferring analog transducer
signals to a data acquisition, monitoring or control system
without the inherent noise, non-linearity, drift and extraneous
voltages. The modules are designed to directly accept analog
signals from Thermocouples, RTD’s, AC and DC Strain Gages,
Torque Transducers, Frequency Transducers, LVDTs, millivolt
or process current signals. The modules amplify, isolate,
linearize and convert the transducer output signals to
standardized analog inputs for high-level analog I/O
subsystems. The 3B Series Subsystem consists of a 10” relay
rack with universal mounting backplane and a family of plug-in
(up to 16 per rack) input and output signal conditioning
modules.

Eight and four channel backplanes are also available. Each
backplane incorporates screw terminals for sensor inputs and
current outputs and a 26-pin connector for high-level single­ended voltage outputs to the user’s equipment.

The input modules feature complete signal conditioning
circuitry optimized for specific sensors or analog signals and
provide two simultaneous high-level analog outputs: 0 to +10V

10V) and 4-20 mA (or 0-20 mA).

(or +

Rev. 0

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However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.

FUNCTIONAL BLOCK DIAGRAM

Figure 1. 3B32 Functional Block Diagram

Output modules accept 0 to +10V (or +10V) single-ended
signals and provide an isolated 4-20 mA (or 0-20 mA) process
signal. All modules feature a universal pin-out and may be
readily hot-swapped under full power and interchanged without
disrupting field wiring.

The Analog Devices 3B Series Signal Conditioning Subsystem is
designed to easily handle signal conditioning problems in
measurement and control applications. Some typical uses are in
microcomputer-based data acquisition systems, programmable
controllers, analog recorders, dedicated control systems, and any
other applications where monitoring of temperature, pressure,
flow and analog signals are required. Since each input module
features two simultaneous outputs, the voltage output can be
used to provide an input to a microprocessor-based data
acquisition or control system while the current output can be
used for analog transmission, operator interface, or an analog
backup system.

Each input module is a single-channel signal conditioner which
plugs into a socket on the backplane and accepts its signal from
the input screw terminals. All input modules provide input
protection, amplification and filtering of the input signal,
accuracy of +

0.1%, low drift of +1 uV/oC (low-level input
modules), and feature two high-level analog outputs that are
compatible with most process instrumentation. The isolated
input modules also provide +

1500 V peak isolation.

The choice of a specific 3B module depends upon the type of
input signal. Input modules are available to accept millivolt, volt,
process current, thermocouple, RTD, AC and DC strain gage,
frequency and LVDT inputs. The voltage output of each module
is available from the system I/O connector while the current
output is available on the output screw terminals.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
Fax: [phone] © 2004 Analog Devices, Inc. All rights reserved.

www.analog.com

3B32

GENERAL DESCRIPTION

The 3B32 is a single-channel signal conditioning module that
interfaces, amplifies and filters a process-current input and
provides simultaneous precision output voltage and current.
Process-current input signals are measured by reading the
voltage across an external precision 100Ω resistor (supplied).
Model 3B32 performs complete signal conditioning, including
isolating (+
protecting their computer side outputs from damage and loss of
signal integrity, and shielding their inputs from damage from
field-side over-voltage faults up to 220V rms. The current
output withstands 130V rms without damage and interfaces
user equipment through screw terminals located on the 3B
Series backplane. Each plug-in, mix-and-match, hot-swappable
module is easily field calibrated via front-panel zero and span
adjustments for both voltage and current outputs.

3B Series Custom-Ranging Program – Externally­programmable Model 3B32-00, enables the user to configure a
special input range by using the optional plug-on AC1310
ranging card, which houses user-supplied resistors to determine
zero and span. To facilitate selecting resistors, a Windows
program, 3B-CUSTOM, calculates resistor values based on the
user-desired input/output ranges.

1500V peak input-to-output and power) and

3B32

assures long-term stability. At the amplifier input, a stable,
zero-scale input voltage is subtracted from the input signal to
set the zero-scale value. Zero suppression can exceed 100% of
the input range. This is ideal for expanded-scale applications
requiring high-resolution measurement of a selected portion of
an input signal. For user convenience, the zero and span can be
factory configured to meet custom range needs (Model 3B32­CUSTOM) or can be externally programmed (Model 3B32-00)
via user supplied resistors inserted in the optional AC1310 plug­on ranging card. Internal low-pass filtering with a 3Hz cutoff (­3dB) two-pole Butterworth filter enhances both 60 dB normal­mode and 160 dB common-mode rejection at 50/60 Hz,
enabling accurate measurement of small signals in high
electrical noise.

Signal isolation is accomplished by transformer coupling with a
proprietary modulation technique for linear, stable and reliable
performance. The differential input circuit on the field side is
fully floating, eliminating the need for any input grounding. A
demodulator on the computer side of the signal transformer
recovers the original signal, which is then filtered and buffered
and drives a voltage-to-current converter to provide the current
output.

A chopper-stabilized low-drift (+

.

1uV/oC) input amplifier

.

Figure 2

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3B32

3B32 Models Available

Model Input Range Output Ranges1

3B32-00
3B32-01
3B32-02

3B32-Custom

1

Output current range may be user programmed to 4 mA to 20 mA using jumper supplied.

2

Requires AC1310 ranging card.

* Custom Input/Output ranges are available. Refer to configuration guide.

Externally Programmable2 -10 V to ±10 V & 0 mA to 20 mA

4 mA to 20 mA 0 V to ±10 V & 4 mA to 20 mA

0 mA to20 mA 0 V to ±10 V & 4 mA to 20 mA

* *

3B32 Specifications
(typical @ +25°C and ±15 V dc, and +24 V dc Power)

Description Model 3B32

Input Ranges

Standard Ranges 0 mA to 20 mA; 4 mA to 20 mA
Custom Ranges 0 mA to 20 mA (refer to ordering section)

Output Ranges

Voltage (RL > 2 KΩ)
Current (RL = 0 to 850Ω)1
Maximum Current Output Span 0 mA to 31 mA

Initial @ +25°C ±0.1% Span
Nonlinearity ±0.01% Span

Stability vs. Temperature

Voltage Output
Zero ±25 ppm of Span/°C
Span ±25 ppm of Reading/°C
Current Output3
Zero ±25 ppm of Span/°C
Span ±25 ppm of Reading/°C

Zero and Span Adjustment Range4

0 V to +10 V; -10 V to +10 V
4 mA to 20 mA or 0 mA to 20 mA

Accuracy2

±5% of Span

Input Resistor

Value
Accuracy ±0.1%
Stability vs. Temperature ±0.002%/°C
Input Bias Current

100 Ω

+3 nA

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