Smart Brownfield: Bringing IoT Connectivity to Legacy Industrial Sensors with LPWAN

BehrTech Blog

“Smart Brownfield:” Bringing IoT Connectivity to Legacy Industrial Sensors with LPWAN


Industries around the world are undergoing a major digital transformation. According to a new market research report, the Industrial IoT (IIoT) market will be worth $110.6 billion by 2025. From manufacturing and logistics, to oil and gas and agriculture, IoT provides undeniable benefits and opportunities for optimization, efficiency, asset management and industrial control.

As optimistic as it sounds, the realization of IoT initiatives is inherently challenging. One of the biggest obstacles is found right where IoT starts – gathering operational data at the edge and communicating it to the cloud.

Most legacy assets, machines and equipment were not designed to connect beyond industrial facilities, creating huge data silos across the organization. This leaves companies with two choices: building entirely new, greenfield plants with new IoT technologies or updating brownfield facilities for IoT connectivity. Since a substantial upfront investment makes a “rip-and-replace” approach to industrial IoT mostly infeasible, the demand for gathering data from legacy industrial sensors and systems such as 4-20mA sensors, will continue to rise.

The 4-20mA Challenge

The 4-20mA current loop is a widely adopted and versatile analog signalling standard found in brownfield industrial sensors. Today’s 4-20mA sensors can track a variety of variables, including temperature, pressure, humidity, and water levels. In a current loop, these process variables are gathered by the sensors and then converted into a proportional current value between 4 and 20mA. Traditionally, these signals are then sent to the process controller via wiring to trigger responses on actuators. For example, a 4-20mA current loop configured to measure tank water levels might assign an empty tank a value of 4 milliamps and a full tank a value of 20 milliamps. In this case, an electrical current of 12 milliamps would imply the water tank is half full. Likewise, from a temperature perspective, operators could assign 4 milliamps to 0 degrees Celsius and 20 milliamps to 100 degrees Celsius in which case 10 milliamps would translate to 37.5 degrees Celsius. Readings below or above these thresholds would signal to operators that there is a temperature issue.

While 4-20mA current loops are versatile and simple to configure for process controls, they also pose a significant challenge. Data flows from these industrial sensors operate within a closed-loop and stay locked on the factory floor. This creates huge data silos across the organization and prevents users from obtaining a comprehensive picture of what’s happening with their equipment, processes and facilities. Furthermore, in many cases 420-mA networks require complex wiring to transmit the output signal to a receiving device, such as a distributed control system, a programmable control system, a data acquisition system, a recorder, or an indicator. In many indoor and outdoor industrial environments, running cables is complex, cumbersome and expensive.

Creating a “Smart Brownfield” with LPWAN

The concerted effort in gathering data from legacy industrial sensors and systems will become a top priority in 2021 and beyond. 4-20mA sensors are, and continue to be, widely used in enclosed industrial networks to measure and report critical variables to a local controller for automation and control tasks. As such, a retrofit IoT solution that adds robust, scalable and long-range IoT connectivity to 4-20 mA devices will open immense possibilities for better operational oversight and planning, especially when it comes to remote assets and systems.

In particular, plug-and-play low-power wide area network (LPWAN) connectivity solutions are easing IoT integration with legacy equipment. For example, an IoT wireless transmitter embedded with 4-20 mA interfaces can draw process data from field sensors and send it to a remote base station using LPWAN connectivity. Besides minimizing infrastructure requirements and production downtime, this solution also offers the benefit of power independence because the transmitter can operate on batteries that last for years. This permits a simplified and wide-scale deployment that can gather vast data from legacy assets and equipment while drastically reducing costs. Furthermore, next-gen LPWAN technologies provide the interference immunity and deep indoor penetration needed to overcome the physical obstructions and environmental complexities of industrial campuses to ensure reliable data communications from these devices at all times.

Today’s LPWAN solutions also offer flexibility and interoperability with existing IT infrastructure and business applications for data management, visualization and machine learning, while ensuring effective integration with future devices, systems and applications.

Given their establishment in the industrial world, 4-20mA industrial sensors will remain a fundamental component of industrial operations for years to come. With the advent of plug-and-play LPWAN connectivity, updating brownfield equipment for IoT is no longer an expensive and daunting task. By breaking down data silos and tapping into unprecedented operational insights in real-time, the opportunities to enhance operations and bolster competitive edge are endless.


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