Single-pair Ethernet benefits for manufacturers

Single-pair ethernet (SPE) has been gaining attention in recent years and has many potential applications and advantages for manufacturers.

By Suzanne Gill May 23, 2022
Image courtesy: Brett Sayles

Single-pair ethernet (SPE) describes Ethernet transmission via a single copper cable pair. In addition to data transmission via Ethernet it also supports the simultaneous power supply of the end devices via power over data line (PoDL).

SPE is an evolution of Ethernet technology that is transforming data accessibility and device control in industrial automation applications. Compliant SPE solutions include connectivity for IP20 and IP67 applications and offer a cable solution that delivers the 1000m reach, indicated in the IEEE 802.3cg 2019, 10BASE-T1L standard.

Explaining more about the technology Stuart McKay, product marketing manager at Panduit, said, “SPE provides a solution focused on industrial reliability and simple field termination, allowing fast deployment, testability and simple reconfiguration while minimizing the risk of polarity errors and physical layer debug issues. Ethernet has become the platform for communications applications and SPE can replace legacy serial controls, delivering more bandwidth at a greater distance – up to 1000m – with power of between 25 to 50 watts. Ethernet continues to support new services such as Power over Ethernet (PoE), Wireless, WiFi 6 and 5G.”

Enabling IIoT with SPE

McKay pointed out standardization of operational technology (OT) and  Internet of Things (IoT) onto a single protocol is critical to drive widespread adoption of digital transformation. He said: “SPE is viewed as the enabling technology that standardizes industrial control networks and digital buildings onto one Ethernet protocol. In the OT arena, SPE is viewed as the new fieldbus solution with a roadmap and applications extending into the future.

Exponential growth of the e-commerce industry, with advances in robotics, and the emergence of IoT continue to challenge organizations to take advantage of Ethernet and SPE. The physical infrastructure is the foundation that supports new technologies allowing efficiencies in production systems and facilities for product fulfillment, distribution and warehousing.

Designing for the manufacturing environment requires a keen knowledge of industry standards to ensure the infrastructure supports various environments on the plant floor. “Considerations such as shock and vibration, temperature, washdown areas, exposure to acids or oil mixtures, and electromagnetic noise must be considered when selecting solutions to support these harsh environments,” McKay said. “Solutions must offer the physical infrastructure for harsh environments which support new technologies, allowing manufacturers to share information in new ways to support increasing production demands.”

Multiple varieties of copper cabling media are available based on the speed and volume requirements. Typically, Category 6 or 6A copper cable is used for enterprise and manufacturing network connections. As these improve, the ability to transmit power over Ethernet continues to increase. It is now possible to power devices with requirements of up to 51 watts over a single cable. Across larger networks of machines and edge devices there often is the requirement for micro data centers (MDC) within the topology.

“The use of patch panels for connections in a MDC provides for essential testing and diagnostic points between equipment and field connections. The benefit of adding a patch panel is that it provides diagnostic points directly in the MDC. This gives the ability to speed network troubleshooting and accommodate future expansion as network speeds increase or equipment connectivity ports change,” McKay said.

McKay went on to highlight another attractive prospect of single-pair power over Ethernet (SPoE) which is specifically defined to work with the 10BAST-T1L 10Mbps protocol.

“OT devices require both data and power to operate effectively and SPoE expands on PoE capabilities allowing easy install and maintenance. Compliant switches and endpoints allow upgrades and additions to be implemented quickly and with ease. PoE and SPoE offer the potential to reuse existing twin-axial cable media. Many of today’s facilities have legacy single-pair twisted cable, much of it is of the shielded variety. If it is the required quality, this can be reused as SPE/SPoE cable media if properly tested and verified and has the potential to meet electrical performance relative to the TIA-568.5 standard for 10BASE-T1L link transmission parameters.”

Given its economy of scale, lower media cost, extended reach, flexibility of design, potential cable reuse and reduced installation labour, SPE (10BASE-T1L) may prove to be a very cost effective alternative to standard 2/4-pair Ethernet deployments for a wide range of edge device connectivity.

SPE is an overdue technology

Sebastian Richter, head of product management Global Business Unit Connectors at Murrelektronik said the process industry is well overdue for an Ethernet-based system to replace today’s subsystems – such as Profibus or HART.

“The desire for consistent communication, higher functionality and more diagnostic options is a reality now enabled by SPE. The interest in the process industry is therefore currently much greater than in factory automation. In contrast to the process industry, plants and machines which already speak Ethernet for the most part, the selection of suppliers with available equipment and components is correspondingly large. Therefore it is more difficult on the customer and supplier side to highlight the added value of SPE technology when carrying out the technological change.”

Discussing the benefits of replacing a four-wire cable with a two-wire cable, with a view to higher data rates, Richter said the advantage of SPE is even more evident than in the range of 100 Mbit/sec Ethernet. “Today, four pairs of wires are required for gigabit applications. For users and manufacturers of assembled cables, this requires a great deal of effort and a high degree of accuracy when connecting the connectors.

“The available installation space is also often limited, especially with M12 connectors – and any inaccuracy in the assembly will result in performance losses. This is where the SPE two-wire technology shows its true strength, because connecting two wires is much easier, faster, more fault-tolerant and therefore more cost-effective.”

Richter went on to highlight the possibilities that open up with regard to hybrid connectors by using the gained installation space in the mating face for an integrated power supply. Data and power are integrated in one connector, which further reduces the installation effort.

Richter said for the process industry, the SPE standard offers for the potential of end-to-end Ethernet-based communication across all areas of the company.

“Interfaces in the form of gateways are becoming superfluous because today’s systems, such as Profibus or HART, are being replaced by Ethernet-based SPE technology,” he said. “For users, this brings consistency, more performance and a higher range of functions, especially with regard to diagnostics. In factory automation, Ethernet-based communication is already state-of-the-art. The transition from Profibus to Ethernet has been underway for many years and is almost complete. Most manufacturers already offer an extensive portfolio of Ethernet-based products and in this sector it is important to solve the current disadvantages of the existing installed base, through the use of SPE technology, in order to arouse customer interest.

Improving efficiency

According to Maurice O’ Brien, strategic marketing manager, Industrial Automation at Analog Devices, 10BASE-T1L SPE will dramatically change the automation industry by improving operational efficiency through seamless Ethernet connectivity to sensors and actuators. “10BASE-T1L solves the challenges that, to-date, have limited the use of Ethernet to sensors and actuators in automation applications,” he said. These challenges include power, bandwidth, cabling, distance, data islands, and intrinsically safe Zone 0 (Process Automation Hazardous Areas) applications. By solving these challenges for both brownfield upgrades and new greenfield installations, 10BASE-T1L will enable insights that were previously unavailable – such as combining process variables, secondary parameters, asset health feedback, and seamlessly communicating them to the control layer and to the cloud. “These new insights will awaken new possibilities for data analysis, operational insights, and productivity improvements through a converged Ethernet network from the sensors to the cloud,” continued O’Brien.

He went on to point out that, by converging on 10BASE-T1 SPE as the method of communication to sensors and actuators, the need for complex and power-hungry gateways is removed. This also enables a transition from the fragmented legacy communications infrastructure that has created data islands where access to the data within sensors and actuators is limited. “By removing these gateways, the cost and complexity of legacy installations is significantly reduced and the data islands they created are removed,” he said. This converged network will deliver a simplified installation, easy device replacement, and faster network commissioning and configuration. This results in faster software updates with simplified root cause analysis and maintenance of field-level assets.


SPE appears to offer the opportunity to take a significant step towards evolving industrial operations and industrial networks edge, by creating a seamless network technology fabric. This will, we are told, provide the platform for the enterprise to gain more control and insight into its underlying processes.

– This originally appeared on Control Engineering Europe’s website. Edited by Chris Vavra, web content manager, Control Engineering, CFE Media and Technology,

Author Bio: Suzanne Gill is editor, Control Engineering Europe.