Single-Pair Ethernet Explained. Benefits and Key Features

Single-pair Ethernet (SPE) has been an absolute game-changer in the world of connectivity. Previously, Ethernet networks relied predominantly on four sets of wires within a cable to transmit data. Using SPE, Ethernet data is transmitted via a single pair of copper cables. This has met the market’s demand for a smaller, lighter, and more cost-effective way to transmit data over Ethernet.

Benefits of Single-Pair Ethernet

Simplified Cabling

Using only one pair of wires, the cabling infrastructure of Ethernet networks becomes far less complex and easier to manage. This also allows users to save both space and weight, which is incredibly beneficial in automotive and industrial applications. Furthermore, with fewer cables, less maintenance is required and installation becomes simplified.

Cost-Effective

SPE’s need for only one pair of wires means you need fewer in your network, thus saving you money. The automotive and aerospace industries benefit from SPE’s cost savings especially. Fewer cables results in reduced weight, which means less fuel is required.

Extended Reach

SPE supports longer cable lengths compared to twisted pair Ethernet. This allows you to cover larger areas without additional equipment like repeaters and switches. This results in more reliable data transmission, even in challenging industrial environments. Of course, this is only applicable under specific conditions, such as lower data rates or better-quality cables.

Greater Versatility

SPE supports various data rates, including 10 Mbps, 100 Mbps, and potentially even 1 Gbps, depending on the specific implementation and cable quality. SPE is designed to be power-efficient and extremely fast, making it suitable for applications that require both real-time data communication and power delivery.

Key Features of Single-Pair Ethernet

Data Transmission Rates

Single-pair Ethernet supports various data transmission speeds ranging from 10 Mbp/s to 1Gbit/s. Faster data transmission rates support an increased number of nodes within the network. Faster transmission rates also help prevent bottlenecks and network congestion , which allows your network to run efficiently.

Ethernet-APL (Advanced Physical Layer)

The Advanced Physical Layer (APL) will define the physical and electrical characteristics necessary to enable reliable communication over a single twisted pair of cables. Designed for extended cable lengths and intrinsically safe power for devices in hazardous areas, APL is the future of factory automation.

Paired with an automation protocol, such as EtherNet/IP or PROFINET, APL will offer advanced error correction and fault detection mechanisms, which enhance the reliability of Ethernet networks. These techniques will help mitigate the impact of transmission errors and improve the overall network performance and uptime. They will also support secure network access control, allowing for granular control and authorization of devices connecting to the network. Unfortunately, APL is still in the final stages of development. More on this later.

Ethernet Standards

Single-pair Ethernet is based on the IEEE 802.3 standards, which helps define the protocols, signaling, and data formats for Ethernet networks. These standards ensure the interoperability between different nodes on your Ethernet network. The IEC 63171-6 standard identifies pin assignments, mechanical dimensions, and electrical characteristics of the connectors used on the network and enables interoperability between nodes. The IEC 63171-6 standard ensures that SPE nodes, regardless of the manufacturer, can communicate without the need for custom cabling.

RJ-45 Connectivity

Single-pair Ethernet typically uses RJ-45 connectors which feature eight pins and are compatible with ports often found in switches, routers, computers, and other networking devices. By using RJ-45 connectivity, you extend the lifespan of your investment into this technology. Rj-45 compatibility ensures that the infrastructure can be adapted to support advanced SPE applications and even faster data transmission rates.

Power over Data Line (PoDl)

Single-pair Ethernet allows for Power over Dataline (PoDl) functionality, which allows both data and power to be sent via ethernet cable. This is especially beneficial for specific nodes--such as wireless access points, IP phones, and security cameras--that would otherwise require power cords. PoDI helps to simplify installation, improve efficiency, and offers greater flexibility and mobility to Ethernet devices.

Why Use SPE in a Factory Environment?

Industrial Automation

Single-pair ethernet provides a high-speed, reliable connection between industrial devices, such as Programmable Logic Controllers (PLCs), motor drives, sensors, and other important network nodes. This allows automated processes to be monitored and controlled efficiently.

Industrial Internet of Things (IIoT)

SPE allows certain IIoT devices to connect to your network. Nodes such as sensors, smart devices, and edge computing systems collect and transmit data and enable advanced analytics for process optimization, resource management, and predictive and preventive maintenance. 

(Future) Fieldbus Replacement

In the not-so-distant future, APL will replace legacy fieldbusses being used on PROFIBUS PA or Modbus TCP networks. Of course, this will only be applicable in non-hazardous environments as Ethernet is not made to sustain a rugged atmosphere. As of this article being written (July 2023), APL is still in development, and device manufacturers will have to begin building devices compatible with the new technology. The overall goal of replacing old Fieldbuses with APL is to increase network flexibility and bandwidth, thus allowing the integration of multiple protocols. However, don’t be fooled--this shift in technology will require organizations to make substantial operational changes.

Why Use SPE in an Automotive Environment?

Cost Efficiency

Before SPE, automotive Ethernet networks would rely on multiple twisted pairs of Ethernet cables. SPE minimizes network complexity as it uses only a single pair of wires for transmitting data and energy. This allows vehicle manufacturers to save money on materials and installation. End users reap the benefits of having a lighter vehicle, such as fuel efficiency. Win-win!

Space Optimization

Modern vehicle networks contain an increased number of electronic components. For that reason, SPE’s thinner and lighter cables are the ideal solution for compact automotive environments. SPE connectors also use less space, which are ideal for crowded spaces where multiple connections are needed.

Higher Bandwidths

As automobiles become more and more technological, so do their electronic components. As a result, automotive networks need greater bandwidth. Single-pair Ethernet supports data rates of up to 1 Gbp/s, providing sufficient bandwidth for various applications in vehicles. Such applications include infotainment systems, advanced driver assistance systems (ADAS), and autonomous driving programs. SPE is designed to support time-sensitive networking (TSN), which is critical for such real-time applications.

Electromagnetic Compatibility

Single-pair Ethernet is designed to withstand automotive environments with a lot of electromagnetic interference (EMI) and noise. To do so, SPE employs advanced shielding techniques and signal modulation schemes that enhance performance.

Single-Pair Ethernet is Worth the Hype

Single-pair Ethernet is changing the factory and automotive environments by introducing a smaller, lighter pair of cables that can transmit both data and energy while supporting greater bandwidths. With the soon rollout of APL, these networks will reap the benefits of advanced error correction and fault detection, not to mention the ability to replace certain fieldbuses in low-stress environments.