Ethernet Replaces the Field Bus

Smart buildings and factories are less expensive and even easier to realize with the Internet of Things (IoT). The components of smart building and factory automation and the structured work area cabling will be united seamlessly via the Internet Protocol (IP).

Application-specific field bus systems thus become superfluous and with them the expensive gateways, complex interfaces, and different protocols.

An important aspect is: High data rates are not mandatory for IoT networks. It is more important to reliably cable the numerous sensors, actuators, and terminal equipment under at times harsh and cramped environmental conditions. Classic copper data cables and RJ45 connectors are theoretically suitable, but over the long term are too large. They would quickly reach their capacity limitations with an increasing number of sensors.

SPE as a lean solution

The Single-Pair-Ethernet (SPE) concept comes from the automotive industry which required lean Ethernet cabling for vehicles. On the basis of xBASE-T1 protocols, SPE can also be used in building and factory automation.

SPE requires – as the name suggests – just a single twisted pair for data transmission. A thin two-core cable and a compact connector are sufficient for the cabling.

In comparison to classic Ethernet cabling, the number of possible connection points is multiplied. The connection to the LAN takes place using switches either centrally in the floor distributor or distributed in the zone at the service outlets.

Single Pair Ethernet works with transmission rates of 10 Mbit/s (10BASE-T1) to 1 Gbit/s (1000BASE-T1). The link ranges are 15 to 1,000 meters. What is more, SPE cabling can supply the terminal equipment with up to 50 watts with Power over DataLine (PoDL).

In international standardization committees, manufacturers such as R&M are currently defining how SPE and the possible applications should be used. Furthermore, R&M plays a leading role in the standardization committees and was involved in the joint development of an SPE connector. Predictions suggest that the first terminal equipment and applications based on 10BASE-T1 will be launched in 2020.

Advantages of SPE at a glance

  • Continuous IP-based transmission
  • Manufacturer-neutral standard products
  • Field bus systems no longer necessary
  • Synergies reduce operating expenses
  • Inexpensive, lean, light cables
  • Space-saving and cables quick to lay
  • Significantly higher connection density than with RJ45
  • Transmission rates to Gbit/s
  • Range up to one kilometer
  • Remote power supply over cables


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Matthias Gerber

By Matthias Gerber

Market Manager LAN