Product Overview

Click to enlarge - 931_collage_4c

Bulletin 931 Analog Signal Conditioners

Analog Signal Conditioners are designed for use with Rockwell Automation I/O systems to provide reduced installation and maintenance costs in process applications. The products are available with two way isolation (between input and output) or three way isolation (between input, output and power).

Bulletin 931H - High-Density Series

The modules in the High-Density series provide cost-effective analog signal conditioning in a very small package.

Bulletin 931S - Standard Series

The Bulletin 931S Standard Series of analog signal conditioners provide solutions for a wide variety of analog signals. They are available in compact sizes ranging from 12.5... 22.5 mm in width.

Bulletin 931U- Universal Series

The Bulletin 931U Universal Series of analog signal conditioners are programmable, allowing the devices to be used on a wide variety of analog signals. Two models are available, one in a 12.5mm wide housing and one in a 45mm wide housing. Both are programmable using software.

More information on Signal Conditioners.

Catalog Number Explanation

931 S A1    A1    N    -    IP    N
   a    b    c    d    -    e    f

Code Description
H High-density
S Standard
U Universal

Input Type
Code Description
A1 0(4)…20 mA
A2 4…20 mA
A3 0…1 A, 0…5 A or 0…10 A AC
A4 0…20 A, 0…25 A or 0…30 A AC/DC
B1 -500 mV…+500 mV
Voltage or Current
C1 0…5V or 0…1V DC
0…20 mA or 4…20 mA
C2 0…10V DC
0…20 mA or 4...20mA
C3 0…10V DC
0…22 mA
C4 ±20mV...±200V
±0.1 mA…100 mA
C9 Universal Inputs
F1 2-,3-wire PNP/NPN, namar initiator, push/pull step
P1 PT 100/2/3/4-Conductor or Ni 100/2/3/4-Conductor
P2 PT 100/2/3-Conductor
P3 PT 100/2/3/4-Conductor
T1 Type J
T2 Type K
T9 Types K,J,T,E,N,R,S,B
V1 24…70V, 70…140V, 140…210V or 210…260V AC/DC

Output Type
Code Description
A1 0(4)…20 mA
A2 4…20 mA
A5 (2) 4…20 mA
Voltage or Current
C1 0…5V or 0…1 VDC
0…20 mA or 4…20 mA
C2 0…10V DC
0…20 mA or 4...20mA
C3 0…10V DC
C5 0...±10V
0…±20 mA
C6 0…5V, 5…0V DC or 10…0V, 0…10V DC
0…20 mA, 20…0 mA or 4…20 mA, 20…4 mA
C7 0…±10V
0...±20 mA
R1 3 A relay contact closure digital output

Configuration Setting
Code Description
N Non-configurable
D DIP Switch
J Jumper
C Computer

Power Type
Code Description
IP Input Loop Power
OP Output Loop Power
BC Aux AC or DC Power
DC DC Aux Power
MC from the Measuring Circuit

Code Description
1 One Channel
2 Two Channels
Hall Hall Effect Sensor
Hart Hart Communication Protocol
Cable Cable
1R One Relay
2R Two Relays

Typical Applications

Analog signal conditioners are used wherever temperature, pressure, level, flow, weight, speed, etc. is measured and controlled as part of a continuous or batch production process. Analog signal conditioners help to prevent these measurements from being degraded on their way from the field to the control room by providing protection from external influences or problems that result from the installation methods used. Typical industries include power plants, steel production, water and wastewater plants, oil and gas production, and chemical processing.

Click to enlarge - Oil Application_4C

Analog Signal Processing

Analog signals involve the measurement of constantly changing physical operating characteristics which come in many different forms, the most common of which are temperature and pressure. These signals are often found in processes that involve harsh industrial environments or are exposed to the elements. Such environmental conditions can significantly affect the quality of the transmitted signal and are also constantly changing themselves. Additionally, such industrial processes often require that these signals are able to be accurately transmitted over long distances.

For these and a variety of other reasons, analog signal conditioning is often required between the measuring instrumentation and the control system. Analog signal conditioning is a long established practice in many process industries such as oil and gas processing, pharmaceutical and chemicals industries and standardized electrical signals are normally used. Currents of 0...20 mA or 4...20 mA and voltages of 0...10 V DC are the most often specified by controls engineers.

Product Range

Rockwell Automation offers a wide range of products to condition analog signals according to industry standards. The Bulletin 931 Analog Signal Conditioners also provide the necessary isolation of the field measurement device from the controller as well as from any external power supplies. Such isolation prevents interference that can occur due to ground loops or common mode noise. The wide range of Allen‑Bradley Bulletin 931 Analog Signal Conditioners completely covers the functions involved in analog signal conversion, isolation, and monitoring. The product range addresses nearly all applications in industrial measuring technology and safeguards the elementary functions between field signals and control systems. The products are easily mounted on 35 mm DIN rail and come in standard electronic housings with widths of 6, 12.5, 17.5, 22.5, or 45 mm.

Analog Signal Conditioners

Given the wide variety of analog I/O available with today’s modern industrial and process control systems, some may question why Analog Signal Conditioners are used. Here are a few examples of why an Analog Signal Conditioner might be desirable or required in an installation.

  • Local Alarm/Indication

  • Many analog signals are passed to local indicators and alarms, which then need to be isolated from each other.

  • Long Distance Transmission

  • Instead of running expensive cable to the control system (e.g., thermocouples for temperature), Analog Signal Conditioners can isolate and convert to a high level signal that is easier to transmit (e.g., 4...20 mA).

  • Non-Isolated Analog I/O

  • If the existing control system does not provide isolated analog inputs, a separate Analog Signal Conditioner will often be used to provide signal isolation when required e.g., if the control system needs to be protected from electrical noise pulses on its analog inputs

  • Isolation of the Power Source

  • Where the control system cannot provide power for the sensor / transmitter, it is often convenient to provide isolation of the power source using an Analog Signal Conditioner.

  • Local Display and Linearization

  • When a dedicated local display is required, the analog signal can be split using an Analog Signal Conditioner. For example, where a liquid volume indicator is needed for filling a bulk storage tank, but the measurement is level (level to volume conversion depends on the shape of the tank).

  • The remaining I/O available in an existing system does not provide for the input type of the sensor required.

  • Example: The remaining I/O in the control system requires a 4...20mA analog inputs and the sensors provide less common signals – e.g., 0…20mV, 2...10V, 0...1mA, 4-12kHz, 0...5 A (AC), etc.

    Click to enlarge - TwoWayIsolation

    Analog signal conditioners with 2-way isolation separate the input and output signals from each other electrically and decouple the measuring circuits. Potential differences caused by long line lengths and common reference points are eliminated. The electrical separation also protects against irreparable damage caused by over voltages as well as inductive and capacitive interference.

    Click to enlarge - ThreewayIsolation

    Analog signal conditioners with three-way isolation separate the supply voltage from the input and output circuits as well and enables the analog circuit to operate with just one operating voltage.

    Click to enlarge - PassiveIsolation

    Analog signal conditioners with passive isolation offer an additional advantage in that they do not require an additional voltage supply. The power supply to the analog signal conditioner can be provided either by the input or output circuit. This current loop feed is characterized by very low power consumption.

    Click to enlarge - Temperature MeasurmentPT100

    A number of analog signal conditioners are available for temperature measurements. For example, PT100 signals in 2-, 3- and 4-wire systems are converted into standard 0...20 mA, 4...20 mA and 0...10V signals.

    Click to enlarge - Temperature MeasurmentTherm

    Analog signal conditioners for connecting conventional thermocouples are fitted with cold trap compensation as standard. These devices amplify and linearize the voltage signal provided by the thermocouple. This guarantees accurate analog signal conditioning while eliminating sources of interference or error.

    Click to enlarge - FrequencyConversion

    Analog signal conditioners are available to convert frequencies into standard analog signals. Downstream controls can therefore directly process pulse strings for measuring rpm or speed.

    Click to enlarge - Current Monitoring

    Analog signal conditioners are available for current monitoring for currents up to 60A AC or DC. These devices cause a switched output to be triggered by currents above or below the set value and may also provide analog outputs for continuous monitoring of the load current.

    Click to enlarge - Voltage Monitoring

    Analog signal conditioners are available for voltage monitoring of both AC and DC voltages. Voltage fluctuations due to switching processes or overload conditions can be detected for voltages above or below the user-defined switching threshold.