Single-Pair Ethernet Standardized for Smarter, Scalable Machine Design

Single-pair Ethernet (SPE) is gaining recognition as a streamlined industrial networking solution that simplifies how components in machine design communicate, power and integrate. Recent insights from industry experts during a press briefing with several EndeavorB2B media brands (including Machine Design) highlight the technical attributes, adoption trends, challenges and practical benefits of SPE.

Simon Seereiner, Single-Pair Ethernet System Alliance (SPESA) board director, and business development manager at Weidmuller Global, describes single-pair Ethernet as “standard Ethernet on just two wires,” noting that the technology was first incorporated successfully in automotive systems for autonomous driving networks. “If you drive a modern car—a Tesla, for example—you are already sitting inside a single-pair Ethernet network…it brought so many benefits to the industry,” he said during the briefing.

At its core, SPE reduces the number of conductors required for data and power transmission from multiple pairs used in traditional Ethernet cables to a single twisted pair. Power over a data line (PoDL) technology allows for power and communication over the same two wires, simplifying connectivity substantially, according to Seereiner. “Gateway-less transparent, deterministic, high-speed communication,” he said, “from the field device up into the cloud.”

SPE is an open standard, internationally ratified by IEEE and ISO, and is supported by major industrial organizations including PROFINET and ODVA, who have collaboratively developed frameworks to ensure interoperability spanning factory and process automation, Seereiner said.

For multidisciplinary engineers tasked with specifying and integrating components in machines, SPE’s characteristics directly impact component design, machine architecture and system integration flexibility. For instance, smaller connectors and cabling facilitate compact machine designs. Ken Crawford, senior director of automation at Weidmuller USA, highlighted the mechanical advantages stemming from SPE's physical layer simplification. “You get higher density of connectors, smaller cable needs, lighter cable, smaller bend radius,” he said.

These features mean components such as sensors, actuators and motors can have smaller or fewer cable entries for tighter packaging and improved internal routing within control cabinets and moving machine parts. The reduced cable bulk improves bend radius compliance on doors or robotic arms, reducing mechanical stress and potential cable failure points.

The intention of a unified Ethernet network is to simplify integration and speed development. Single-pair Ethernet leverages standard Ethernet protocols to integrate with existing infrastructure and software ecosystems, according to Crawford. “SPE is a unified network,” he said. “Everyone knows Ethernet…you still get to retain all of your drivers and interoperability.”

This common protocol foundation lowers the complexity of integrating devices from different vendors, simplifying component firmware development and reducing system validation time. For designers, this translates to reduced engineering effort and faster time to market via standardization.

Long Cable Runs, Multi-drop Capability

Arnold Offner, APL and SPE ambassador, Automation Infrastructure, Business Unit, Americas at Phoenix Contact, explained that SPE supports cable runs up to 1,000 meters, similar to or exceeding traditional analog 4 to 20 mA loops, but with higher data speed. This enables flexible component placement across larger machines and facilities without requiring costly repeaters or intermediate in networking equipment, encouraging modular machine designs with distributed intelligence.

SPE supports multi-drop configurations over shorter distances (5 to 15 meters) within control cabinets, allowing multiple devices to share a single network port and cable. “You can use a single port multi-drop on your machine to talk to multiple sensors off of one cable, which accelerates adoption and simplifies the machine.” Crawford said. This minimizes port count and cabling complexity, which it seems would be especially beneficial to smaller machine builders with limited engineering resources.

Cybersecurity Integrated at the Component Level

Seereiner noted the cybersecurity advantages that SPE inherits from Ethernet. “It would be a huge amount of work to make CANbus, Modbus or IO-Link cybersecurity,” he said. “Ethernet is designed for security.”

Crawford added that SPE uses the same firmware and network management tools as standard Ethernet hardware. “You basically have one-to-one transfer with zero development in order to attain the same level of security as you have today,” he said.

Components incorporating SPE interfaces can be monitored, patched and updated remotely with existing IT/OT security infrastructure, which Machine Design has reported is a concern for connected machines.

When it comes to the difference between SPE and Ethernet advanced physical layer (APL), another industrial two-wire Ethernet standard, Offner said, “APL is designed to be intrinsically safe and support hazardous environments with cable lengths up to 200 meters. SPE supports longer cable lengths and is mostly for non-hazardous zones.”

Seereiner added that many process industry sensor makers develop products compatible with both SPE and APL, which share the underlying IEEE 12Base-T1L physical layer standard. The essential difference lies in APL’s added safety features for hazardous areas, he said.

Industry Adoption, Outlook

When asked about a report statistic that indicated 44% of surveyed industrial automation specialists said their organizations expect to adopt single-pair Ethernet within two to four years, Seereiner replied, “By 2030, we expect up to 50 million SPE nodes in factory automation and 12 million in building automation.”

The increasing awareness among engineers, especially younger cohorts, is driving demand for evaluation samples and pilot projects, according to Seereiner. “I’ve seen many engineering departments asking for the first samples. Then they come back after testing and decide on production plans,” he said.

Offner noted that regulatory and cybersecurity challenges can slow progress but maintained that SPE adoption remains on track.

Seereiner compared SPE’s trajectory to PROFINET’s rollout over the last two decades but expects faster initial adoption because Ethernet is now a well-established baseline skillset among engineers.

Practical implications of SPE adoption for the readers of Machine Design can include:

• Component size and integration. Smaller connectors and cabling reduce design constraints, allowing for more compact sensors and devices.
• Cable management. Lighter, more flexible cables allow more efficient routing and reduce mechanical wear.
• Network architecture. Engineers can design distributed control and sensing networks with longer cable runs but fewer network elements.
• Security and maintenance. Built-in Ethernet security simplified handling of cyber threats through centralized management.
• Interoperability. Standardized Ethernet fosters multi-vendor interoperability and easier integration.
• Adoption of SPE-capable components early in the design phase can facilitate building machines that are potentially smaller, more flexible, easier to maintain and scalable to future networking.