Technical FAQs

4 – 20mA Output Signal

2-wire loop powered

The 4-20mA output signal is an analog output signal commonly used in sensors. It is typically powered by DC voltage ranging from 8-32 VDC, which are widely available commercially.

Occasionally, 4-20mA output signals use a three wire configuration (+V, -V, +S), but the vast majority of modern 4-20mA output sensors employ a two-wire, loop powered configuration with a supply (+V) and ground (-V). The current (mA) is measured on the loop by reading the voltage across a known value resistor (often called a sense resistor).

Nearly all industrial level products from Core Sensors offer 4-20mA output options.

4-20mA Wiring Schematic – How To Guide

For this how to guide, there are three components; power supply, Core Sensors pressure transducer, and a meter or other DAQ system.

1) Power Supply – The first component to the current loop is the power supply, capable of delivering 10-28VDC. The positive (+) terminal of the power supply is connected to the +V pin or wire of the transducer.

2) Core Sensors Pressure Transducer – The -V pin or wire of the transducer is connected to the milliamp input terminal of the meter or DAQ.

3) Meter or other data acquisition (DAQ) – The Common (COM) terminal of the meter or DAQ is then connected to the negative (-) terminal of the power supply. This final step is important as it completes the current loop.

* In certain circumstances, there may be an additional pin or wire used as a case ground. This connection is not critical to the current loop but may be critical to maintain listed certifications of the transducer. Please refer to the Core Sensors wiring guides to verify wiring prior to installation.


  • Noise Immunity
  • No signal loss over long transmission distances
  • Compatibility with various power supplies and PLC’s because of high usage in general industry


  • Current consumption is high when compared to a voltage output sensor
  • Need for at least 10VDC excitation, making for limited battery-powered options

Millivolt Output Signal

The millivolt output signal is the oldest signal, yet still has popular uses today. Sensors with millivolt output can be roughly separated into two categories; compensated and uncompensated. Compensated sensors are generally ones where the output has been trimmed with resistors to have a set zero and span tolerance, along with a specific sensitivity (commonly 5 or 10mV/V) over a specified temperature range such as 0-55°C. Uncompensated millivolt output is generally the raw output of the sensor that has not been adjusted or trimmed, and is usually stated with a typical output range, such as 100mV output, +/-25mV @ 10VDC excitation. With either choice, one common advantage of millivolt output is the response time to changes in pressure. The frequency response time of millivolt output sensors is fast because there are no circuits to slow down the signal changes.

Choosing compensated vs uncompensated depends on the needs of the application. If the application includes a signal conditioner that simply amplifies the sensor output, compensated is usually the better choice because the sensor is already set to meet published performance over a specified temperature range. If the application is one where the equipment will be characterized and compensated/error corrected as a whole using a signal conditioner that can set zero, span, and temperature compensation, an uncompensated output is a good choice because it maximizes that output available for adjustments and error correction.

In physical terms, one of the primary advantages of millivolt output sensors is size and packaging flexibility. Because there are no ICs and other large electronic chips to fit inside the sensor housing, millivolt sensors are more flexible in design to fit into embedded systems and customized equipment.

Millivolt Wiring Schematic

How To Guide

For this how to guide, we have three components; power supply (labeled as 1 in the schematic), Core Sensors pressure transducer, and a meter or other DAQ system (labeled as 2 in the schematic).

1) Power Supply – Connect the positive (+) terminal of the power supply to the +V pin or wire of the transducer. Connect the negative (-) terminal of the power supply to the Ground (GND) pin or wire of the transducer.

2) Meter or other data acquisition (DAQ) –  Connect the COM terminal of the meter of DAQ to the -Signal pin or wire of the transducer. Connect the Volts input terminal of the meter or DAQ to the +Signal pin or wire of the transducer.

This will complete the 4-wire circuit.

* In certain circumstances, there may be an additional pin or wire used as a case ground. This connection is not critical to the output signal but may be critical to maintain listed certifications of the transducer. Please refer to the Core Sensors wiring guides to verify wiring prior to installation.


  • Noise resistance due to lack of ICs.
  • Fast response time to changes in pressure.
  • Perfectly ratiometric, so any power supply will work (up to the max VDC)
  • Flexible design possibilities for embedded systems


  • Requires 4-wire connection
  • Possible low signal to noise ratio in applications where EMI/RFI is present
  • Limitations on signal transmission distances
  • Often requires external/additional signal conditioner

Common Applications

High Performance Liquid Chromatography (HPLC) – mV sensors are common in HPLC because often the system and pumps are calibrated as a whole and/or the system already has an on-board signal conditioner with trimming features to re-calibrate the equipment when needed. Also, mV sensors can be made as custom embedded units more easily, resulting in lower “dead volume”, which is important in HPLC applications to reduce cross-sample contamination.

Mass Flow Controllers (MFC) – Use of mV sensors in MFCs is common for similar reasons as the HPLC, with the additional need for fast response time. The fast response time of mV sensors in the MFC is vital to fine tune the amount of product that is allowed to flow into the process.

Scales and weighing equipment/hydraulic press and forming – mV sensors are used in hydraulic weighing and machine press applications to replace load cells. The mV output of the sensors is similar to the mV output of many load cells, allowing OEMs to minimize system redesign when upgrading from a load cell to a pressure sensor.

Higher ambient temperature applications – In applications such as super-heated steam, downhole drilling and MWD, or applications measuring pressure in a engine compartment of a moving or stationary engine, temperatures can climb to a range that is not compatible with ICs and ASICs. Because of the lack of ICs, mV units can generally be installed in locations that are simply too hot for amplified sensors, and the signal is transmitted to a remote signal conditioner. The CS-HTP high temperature pressure sensor and CS-90 downhole pressure sensor are recommended for applications where high temperatures are a concern.

Heating, Ventilation, Air Conditioning, and Refrigeration (HVAC/R) – There are numerous applications in HVAC/R systems where pressure is measured. Often, there is a need for two separate sensors to be used to measure pressure in two spots to provide operators with the differential pressure reading. These PLCs are designed to accept two mV signals and report the differential pressure. The CS10 industrial pressure transducer with a millivolt output signal would be an ideal solution to handle this type of application.

Pressure Sensor Customisation

We can proudly offer a range of custom pressure sensors/transducers to meet the specific requirements of each customer’s application. Selecting the correct sensor can be an intensive task. Together with our manufacturing partners Core Sensors, Emerson Paine and Merit Sensor™️, we are committed to delivering the best solutions for every project. Our engineers are on hand to help narrow down the best end product; if we are not able to provide an off-the-shelf sensor that fits your application, we can explore the avenue of configuring a custom pressure sensors. Below are some examples of how these sensors can be customised:

Process Connections & Fittings

The process connections or fittings of a pressure sensor is a critical component that can be customised to ensure seamless integration into various systems. By adapting the connection we are able to find allows for a perfect fit with the customer’s existing setup or find a best match for the location or environment that the sensor is to be used . This enables the sensors to be easily installed in a wide range of applications such as Aerospace, Downhole. Oil & Gas and Subsea, enhancing functionality and reliability. Our manufacturers offer various connections including Male NPT connectors, UNF, Autoclave, E3, E4, Double o-ring, Differential o-ring, Weldable tube, Internal pipe and Adapters.

Output Signal

Customisation of the output signal is another bespoke option offered by our manufacturers. This modification enables the pressure sensors to communicate effectively with the customer’s equipment, ensuring that data transmission is both smooth and efficient. Whether the requirement is for analogue or digital signals, adjustments can be made to meet the specific communication protocols of the application, facilitating accurate data interpretation. Selecting the appropriate output signal depends on a few pieces of information regarding the application. Is this an existing setup where the output signal is already defined? What is the supply voltage available to power the sensor? How far do you need to transmit the output signal of the sensor? All of these application questions will help guide us to the most appropriate output signal. Some of the options we can offer are:

Pressure Range

Adjusting the pressure range of the sensors allows for accurate and reliable measurements across diverse operating conditions. This customisation ensures that the sensors can perform optimally within the specific parameters of the customer’s application, whether it involves low-pressure environments or high-pressure systems. By offering this flexibility, we can ensure that the sensors provide precise readings, critical for maintaining operational integrity and safety.

Electrical Interface

The electrical interface can also be customised to enhance compatibility with a broad array of devices and ensure the suitability of the connection for the application environment. This tailor-made approach ensures that the sensors can be effortlessly connected to the customer’s equipment, promoting ease of use and integration. Our manufacturers offers a variety of electrical terminations to fit just about any installation. Customers can expect connectors such as:

  • Standard Cables
  • High temperature Cables
  • Solder Hooks (pig-tails)
  • DIN 43650-A and C
  • M12x1
  • Packard Metripack 150
  • 6-Pin Bendix
  • Deutsch DT04 3 Pin and 4 Pin
  • Hermetically sealed connectors

Certain product families have a limited selection of options due to hazardous certifications and design limitations.

Wetted Materials

One of the most important steps when specifying the appropriate sensor for your application is selecting the wetted material of the process connection (or pressure port). Understanding the operational location, temperatures, mounting and proximity to other devices is important. Selecting the proper material, connections and external surfaces of the sensor will help ensure reliable, long term operation.

Consideration of the media (fluid or gas) and temperature that will be measured is vital. The outside surface material (including inside the pressure port), or “wetted material” must be taken into consideration during the selection or design. If the wetted material is not compatible with the environment media being measured, your sensor will degrade over time. Please speak to one of out engineers to discuss the best material for your application.

Our manufacturers are able to offer the below materials on selects sensors:

  • 17-4PH Stainless Steel (UNS S17400)
  • 316L Stainless Steel (UNS S31603)
  • Inconel 718 (UNS N07718)
  • Inconel 725 (UNS N07725)
  • Hastelloy* C276 (UNS N10276)
  • Titanium BT9 (Grade 12)

*Hastelloy® is a registered trademark of Haynes International, Inc.

When creating a custom pressure sensors, each customisation option undergoes a thorough review on a case-by-case basis to assess feasibility and ensure that it meets the specific needs of the application. Rhopoint Components Ltd and our manufacturing partners are dedicated to providing support and expertise throughout the customisation process, ensuring that each sensor is perfectly adapted to deliver optimal performance and reliability.

Contact our engineering team for expert guidance and to explore our customisation options. 01342 330470 |

Voltage Output Signal

1-5V, 1-6V, 0-5V, 0-10V, 0.5-4.5V, 0.5-2.5V

A voltage output signal is an analog output signal commonly used in pressure, temperature, and other types of sensors. Within the realm of voltage output, there are a variety of I/O options, including the ones in the table below.

The most common voltage output signals, especially where power consumption is not an overriding consideration, are 1-5VDC, 1-6VDC and 0-10VDC for industrial applications.

With the growth of IoT & IIoT projects that incorporate sensors, the capability to operate from low power with less current consumption is valuable, especially for equipment being deployed in remote areas where frequent battery changes are costly and time consuming.

To address low power needs, there are a number of voltage output options that can be powered from 3V, 3.3V, 3.7V, 5V, and 9V power supplies and batteries. The voltage output signals commonly paired with these supply voltages are*millivolt, 0.5-2.5VDC non-ratiometric and 0.5-4.5VDC ratiometric. The option for 0.5-2.5VDC output is rapidly growing in popularity because of the increased use of 3 to 5VDC lithium ion batteries.

*See table for excitation voltage requirements.

While the millivolt signal is a ratiometric signal, the term ratiometric is most commonly paired with 0.5-4.5VDC output, which is ratiometric to a regulated 5VDC excitation. The ratiometric output signal 0.5-4.5V output signal became widely popular in automotive and off-road applications. With vehicles using a 12V supply, users could regulate the voltage down to 5V, and create a signal that is proportional to the supply. A 10% reduction in supply from the 5V supply creates a proportional 10% decrease in the output signal. It is still used in similar applications and has also been utilized in industrial applications such as compressors and water pumps.

Output Signal
0-5VDC, three wire
0-10VDC, three wire
1-5VDC, 1-6VDC
0.25 to 10VDC, 1-10VDC
0.5-4.5VDC, ratiometric
0.5-2.5VDC, non-ratiometric
Excitation Voltage
10-28VDC, unregulated
15-28VDC, unregulated
10-28VDC, unregulated
15-28VDC, unregulated
5.0VDC, regulated
3-5VDC, unregulated

3-Wire Voltage Wiring Schematic

How To Guide

For this how to guide, we have three components; power supply, Core Sensors pressure transducer, and a meter or other DAQ system.

1) Power Supply – Connect the positive (+) terminal of the power supply to the +V pin or wire of the transducer. Connect the negative (-) terminal of the power supply to both the Ground (GND) pin or wire of the transducer and the Common (COM) terminal of the meter or DAQ. If using a bench test setup, this is commonly done by using a male to male banana plug to connect the power supply and meter and stacking a banana to alligator clip to connect the power supply to the transducer.

2) Meter or other data acquisition (DAQ) –  Connect the Volts input terminal of the meter or DAQ to the Signal pin or wire of the transducer.

* In certain circumstances, there may be an additional pin or wire used as a case ground. This connection is not critical to the output signal but may be critical to maintain listed certifications of the transducer. Please refer to Core Sensors wiring guides to verify wiring prior to installation.


  • Many signal configurations to fit a variety of electronics options, power supplies and PLCs
  • Low-power, low current consumption options
  • “Live Zero” options improve troubleshooting support (for example, no power vs system/sensor failure)


  • Long cable runs can lead to signal attenuation/signal loss
  • Does not have the level of noise immunity as 4-20mA current output

Common Applications

Tank Level Monitoring – For tank level applications, a voltage output pressure sensor with an IP-68 rating can be packaged with a SCADA system to remotely monitor fuel or water level for remote installations requiring low current consumption due to battery life concerns. The CS12 Submersible Pressure Transducer and CS82 Intrinsically Safe Submersible Pressure Transducers can be manufactured with a low current consumption ASIC to perform in this application.

Oil Field Equipment – In remote oilfields, voltage output pressure sensors and temperature sensors consume less battery life while providing enough signal to measure the media and transmit the signal to the telemetry unit. Data is then sent to the cloud for analysis and monitoring.

IIoT – Industrial applications continue to take advantage of IoT technology. Factories are measuring pressure and temperatures of test equipment as well as automation equipment to maximize efficiency, especially in locations where it is too costly or difficult to run power.

HVAC and Refrigeration – Voltage output signals continue to be a popular option amongst HVAC/R OEM and service installations. Due to the low cost and ease of use, pressure, temperature, and combination sensors can all be quickly integrated with noise immunity within the commonly short distances where sensors are run in HVAC automation applications, such as boiler rooms. Products such as the CS10 Industrial Pressure Transducer can be designed with a voltage output signal for low to high volume applications.

What is a resistor?

A resistor is an electronic component used to resist the flow of electrical current. Resistors are passive components that introduce resistance within the flow of an electrical circuit. A resistor that performs in accordance to Ohm’s law is called an Ohmic resistor. When current is passed through an Ohmic resistor, the voltage drop across the terminals is proportional to the magnitude of resistance. We are able to manipulate these resistances by utilising different materials such as MANGANIN® or ISAOHM® with varying properties such as wire thickness, length or form, all of these factors are able to resist an electrical flow at different rates.

What is an Ohm?

Ohm (Ω) is the SI unit of electrical resistance, named after Georg Ohm, a German physicist. An ohm is defined as the resistance between two points of a conductive medium when 1V (Volt), applied to these points, produces a current of 1A (Ampere). Electrical resistance is measured in SI units and can range from microohm to teraohm, being able to calculate these values in terms of Ohms is key to any electrical equation including resistance calculations.

These values are displayed as:

µΩMicroohmOne microohm is equal to 1/1,000,000 (10-6) of an ohm
MilliohmOne milliohm is equal to 1/1,000 (10-3) of an ohm
ΩOhmOne ohm is the baseline for all other SI unit conversions
KiloohmOne kiloohm is equal to 1,000 (103) ohms
MegaohmOne megaohm is equal to 1,000,000 (106) ohms
GigaohmOne gigaohm is equal to 1,000,000,000 (109) ohms
TeraohmOne Teraohm is equal to 1,000,000,000,000 (1012) ohms

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