The automotive industry: Origin of Single Pair Ethernet

The development of the Single Pair Ethernet (SPE) starts in the automotive industry, where smaller and more powerful devices are required. More and more Ethernet systems are being installed in today's vehicle generations. Only by networking ECUs and sensors can new driver assistance systems be realised - such as LIDAR (light detection and ranging), high-resolution displays, 4K cameras, or infotainment systems. Future-oriented technologies such as autonomous driving also require connection technology that enables higher data rates to be transmitted in a smaller installation space. Other industries can also benefit from this approach.

First official IEEE standards

The development of automotive Ethernet has led to two official IEEE standards: 100BASE-T1 (100 Mbit/s) and 1000BASE-T1 (1 Gbit/s). When defining these standards, the aim was to define the limit values for connectors and cables as well as the measurement methods from the requirements for the entire channel (defined in the IEEE).


Application areas for SPE solutions

Single Pair Ethernet is ideally suited for infrastructure applications in mechanical and plant engineering, process technology, and building infrastructure. The big advantage: Single Pair Ethernet is environmentally neutral, so field devices, sensors, and actuators can be easily integrated into an existing Ethernet environment. Additional gateways and interfaces are not required. Unlike fieldbus protocols, Ethernet transcends all automation levels. It is more universal, efficient, and cost-effective than fieldbus systems.

Advantages for plant engineers:

  • Transmission distances of up to 1,000 m at transmission rates of 10 Mbit/s
  • Transmission distances of 40 m at transmission rates of 1Gbit/s
  • Simple installation using only one pair of wires
  • Reduction of space and weight
  • Lower acquisition costs for new installations
  • More compact cable trays
  • Efficient cabling of several communication participants, thanks to common lines and interfaces (multidrop)
  • Existing cabling can continue to be used
  • Integration of up to four devices

Due to the standardized interfaces, single- and four-pair cabling concepts can be combined with each other, as can IP20 and IP6X solutions. In addition, twisted-pair technology allows the terminal devices to be supplied with power of up to 60 watts via the same wire pair (Power over Data Line - PoDL).

Cable requirements

Different applications have different cabling requirements.
The relevant cabling requirements are listed in the following table:

AutomotiveBuilding AutomationProcess AutomationFactory Automation
Application focusWiring harness
in the automobile
Control cabinet wiring Field cabling (e.g. KNX)Field cabling sensorsInd. control cabinet wiring Field cabling  Field cabling sensors
Transmission rate 
Transmission distance
10 MBit/s –
1 GBit/s  15-40 m
10 MBit/s – 1 GBit/s  < 1000 m10 MBit/s  < 1000 m 10 MBit/s – 1 GBit/s  ≤ 100 m
Conductor cross-sectionAWG 26-22AWG 26-22AWG 22-18AWG 26-22
Mech. / electr. robustnessmedium – highlow – mediumhigh (+Ex)medium – high
Current connectorsAutomotive-specific connectorsIndividual wiring, terminal, EIB, RJ45Terminal, plug connector, M12RJ45, single wiring,
terminal, M8/12

Connection technology in factory automation

With advancing automation, a growing number of sensors and actuators are being used in all areas of production, which must be reliably connected to cloud systems.

Single Pair Ethernet solutions offer significant advantages here:

  • Future-proof: Standardized connectors and cables according to IEC 63171-2 (IP20) and IEC 63171-5 (IP67)
  • Powerful: Ranges up to 1,000 m, data rates up to 1 Gbit/s and performance up to 60 W
  • Efficient: Plug-and-play integration also possible with existing cabling infrastructures
  • Compact: Connector faces for both single- and multi-ports allow high packing densities
  • Easy to integrate: Plug and socket variants for M8 inductive sensors and flying leads

The standardized interfaces according to IEC 63171-2 (IP20) and 63171-5 (IP67) are ideal for office and industrial environments. The cabling, which has been optimized for the specific application, forms the basis for future-proof networking from the sensor to the cloud.

More about standardisation

Connection technology for process automation

In process automation, explosion protection and long transmission distances place increased demands on network technology. The necessary standards are summarized as Advanced Physical Layer (APL).

Single Pair Ethernet solutions offer the following additional advantages for process automation:

  • Standard-compliant: All products meet the requirements of the "APL Port Profile Specification" (Draft 0.3)
  • Flexible: Horizontal, vertical, and angled conductor connection direction for every device design
  • Convenient: Colour coding and marking for easy wiring
  • Safe: Also available for increased safety requirements in EX areas according to IEC 60079-7

Connection technology for building automation

The Internet of Things (IoT) has become an integral part of building automation and will continue to play an increasingly important role in the future. By using the IP protocol, building automation can be implemented both more conveniently and more cost-effectively, since sensors, controllers, and other technical units in the building are directly connected to the building management system. This means that existing proprietary fieldbus systems are replaced by continuous Ethernet cabling, thus eliminating the need for expensive and complex programming and parameterization.

The trend in the development of smart buildings is to reduce the energy consumption of all networked devices. This is another area where Single Pair Ethernet comes into play, as a high-performance transmission of data and power in parallel via just one twisted-pair using Power over Data Line is possible. The Single Pair Ethernet components are also robust and powerful and can be used in a variety of applications due to the different transmission distances and rates in combination with the high packing density.

More about SPE Technology