Single-Pair Ethernet: The Foundation of Next-Generation Industrial IoT

In a modern chemical processing plant, thousands of sensors continuously monitor critical parameters—pressure fluctuations, temperature variations, flow rates—generating massive data streams that need reliable transmission. Traditional fieldbus systems strain under this data deluge, while conventional Ethernet installations create unwieldy cable bundles that consume precious space in control cabinets. This scenario represents a common challenge across industrial environments seeking digital transformation.

Enter Single-Pair Ethernet (SPE)—an elegant solution transforming industrial connectivity by enabling seamless IP communication from sensor to cloud while dramatically reducing infrastructure complexity.

What Is Single-Pair Ethernet?

At its core, SPE transmits standard Ethernet data and power over just one twisted copper pair, contrasting sharply with traditional Ethernet's four or eight wires. Originally developed for automotive applications (IEEE 802.3bw-2015), SPE has evolved to address industrial requirements through standards like 10BASE-T1L, delivering 10 Mbps over distances up to 1,000 meters.

The technology relies on several key standards:

• Power over Data Line (PoDL): Integrates power delivery up to 52W
• Time-Sensitive Networking (TSN): Enables deterministic communication essential for critical industrial processes
• 10BASE-T1L: The primary industrial standard supporting long-distance transmission

Why Does SPE Matter for Industrial IoT?

Traditional industrial networks often involve a patchwork of protocols requiring complex gateways and conversion layers. SPE offers a streamlined approach with compelling advantages:

Space and Weight Efficiency
SPE cables are approximately 50% smaller than traditional Ethernet, making them ideal for space-constrained control panels and industrial equipment. This reduction translates to easier installation and maintenance in crowded industrial environments.

Extended Reach
Perhaps the most striking advantage is distance capability—10BASE-T1L reaches 1,000 meters, ten times farther than standard Ethernet. This extended reach eliminates the need for repeaters in large industrial facilities, reducing points of failure.

Integrated Power Delivery
PoDL technology eliminates separate power cabling requirements for low-power sensors and devices. Have you considered how this affects total installation costs? Beyond material savings, labor reduction becomes significant when deploying thousands of sensors across a facility.

End-to-End IP Connectivity
SPE creates a unified IP-based infrastructure from sensor to cloud, removing protocol gateways required when interfacing fieldbus systems with IT networks. This seamless connectivity forms the backbone of truly integrated Industrial IoT deployments.

Environmental Resilience
Shielded SPE variants withstand the harsh conditions common in industrial settings: vibration, electromagnetic interference, and temperature extremes. This ruggedness ensures reliable operation where consumer-grade networking would fail.

The Surprising Automotive Connection

SPE's industrial potential emerges from an unexpected source: automotive engineering. The same technology enabling sensor networks in vehicles—originally developed as BroadR-Reach—now drives smart factories. This cross-sector migration represents what I would call "technological repurposing"—when innovations developed for one domain find transformative applications in another.

Consider this fascinating development: SPE enables Ethernet-APL (Advanced Physical Layer), a ruggedized implementation designed specifically for explosive environments like oil refineries. The technology that connects dashboard instruments now monitors critical infrastructure in hazardous zones—with intrinsic safety certification.

Real-World Implementation: Industry Transformation Cases

Process Industries: The Early Adopters

Oil and gas companies have deployed Ethernet-APL systems leveraging SPE to monitor pipelines in hazardous zones, transmitting both data and power over distances exceeding 1,000 meters. This implementation allows centralized monitoring while maintaining intrinsic safety in explosive environments.

As Wilhelm Hauser, Chairman of the Ethernet-APL Consortium, noted: "Ethernet-APL represents a critical step toward fully digitalized process industries, enabling seamless communication from field devices to the cloud."

Manufacturing Transformation

Automotive manufacturers have integrated SPE for robotic arm connectivity, reducing cable weight by approximately 30% while enabling direct IP connectivity to end effectors. This weight reduction improves robot performance while the unified network architecture simplifies maintenance and upgrades.

Building Systems Integration

Legacy building automation systems often rely on specialized protocols that complicate cloud connectivity. SPE retrofits enable direct IP networking for HVAC systems, lighting controls, and security devices without requiring complete rewiring—a perfect example of how SPE bridges the gap between installed infrastructure and IoT capabilities.

Implementation Challenges: The Adoption Hurdles

Despite its promise, SPE faces several implementation challenges:

Connector Standardization Issues
Competing connector variants defined in IEC 63171 (including M8 and M12 formats) create potential compatibility concerns. The industry continues working toward standardization, but integration planning must account for these differences.

Ecosystem Development
While major vendors like Phoenix Contact, Harting, and Weidmüller now offer SPE solutions, the overall device ecosystem remains less mature than traditional industrial networking. Early adopters must carefully evaluate product roadmaps and compatibility commitments.

Migration Planning Requirements
Converting existing installations requires thoughtful planning. What communication requirements need to be maintained during transition? How will hybrid networks operate during phased implementation? These questions necessitate detailed migration strategies.

The SPE Adoption Roadmap: A Five-Year Outlook

Looking ahead, SPE adoption will likely follow this trajectory:

2025: Discrete Manufacturing Acceleration

• • Focus: Broad adoption begins in discrete manufacturing sectors.

  • Driver: TSN (Time-Sensitive Networking) integration over SPE.

  • Impact: Enables real-time control, starting to replace specialized fieldbus systems.

2026: Higher Bandwidth Standards

• • Focus: Enhanced capabilities through standardization.

  • Driver: IEEE 802.3dg finalized (100BASE-T1L).

  • Impact: Delivers 100 Mbps over 500m links, expanding SPE use to more bandwidth-intensive applications.

2027: Comprehensive Device Ecosystem

• • Focus: Market maturity and ease of use.

  • Driver: Wide availability of SPE-enabled sensors, controllers, and infrastructure.

  • Impact: Simplifies the process of specifying and implementing SPE solutions.

2028: Brownfield Dominance

• • Focus: Retrofitting existing industrial facilities.

  • Driver: SPE established as the preferred method for upgrades.

  • Impact: Gradual replacement of legacy fieldbuses with unified IP connectivity in brownfield sites.

(Gap Year - Continued Growth & Consolidation)

2030: Default Standard Emergence

• • Focus: SPE potentially becomes the primary choice for new installations.

  • Driver: Widespread acceptance and proven benefits.

  • Impact: Estimated ~70% of new industrial device connections could utilize SPE technology.

Key Takeaways: The SPE Value Proposition

Single-Pair Ethernet represents a fundamental advancement in industrial connectivity with several core benefits:

1. Infrastructure Simplification — Reduced cabling complexity and unified IP networking streamline both installation and maintenance.

2. IT/OT Convergence Enablement — SPE bridges the gap between operational technology and information technology, creating truly integrated systems.

3. Future-Proof Architecture — The technology provides a clear path from current installations to fully realized Industry 4.0 implementations.

4. Comprehensive Cost Reduction — Beyond material savings, simplified architectures reduce engineering, installation, and maintenance costs.

The question isn't whether SPE will transform industrial connectivity—it's how quickly organizations will leverage this technology to gain competitive advantage. Early adopters in process industries are already demonstrating the benefits, with discrete manufacturing positioned to follow.

As industrial facilities continue their digital transformation journeys, Single-Pair Ethernet provides the foundation for truly connected operations—proving that sometimes, technological simplification enables the most sophisticated capabilities.

References

[1] https://de.wikipedia.org/wiki/Single_Pair_Ethernet
[2] https://www.cinch.com/resources/blog/the-benefits-of-single-pair-ethernet-for-industrial-and-smart-building-applications
[3] https://www.single-pair-ethernet.com/en/artikel/single-pair-ethernet-use-cases
[4] https://www.controleng.com/how-to-establish-a-futureproof-industrial-network-with-single-pair-ethernet/
[5] https://my.avnet.com/silica/resources/article/single-pair-ethernet/
[6] https://www.hilscher.com/in/the-hilscher-blog/blog-single-pair-ethernet-enhanced-cloud-access-to-sensors-and-peripherals
[7] The Pragmatic Engineer's Take on Single Pair Ethernet: Turning Challenges into Opportunities
[8] Single Pair Ethernet, the Automotive Ethernet
[9] 100Base-T1 vs 100Base-TX Ethernet
[10] Single Pair Ethernet in industry - great technology, thwarted by the connector war?
[11] Time Sensitive Networking: Transforming Industrial Communication with Deterministic Ethernet
[12] The role of Single Pair Ethernet in IoT development