Industrial communication via SPE technology

By Karl Lehnhoff   |   January 25, 2023   |   Provided By EBV Elektronik

Having communication protocol compatibility across the entire network will mean that there is no longer a need for translating data. Consequently, network infrastructure will be more reactive, cheaper to implement, easier to maintain and have markedly greater scalability.

Though Ethernet is now the backbone of the vast majority of industrial networks, things get more complicated when you reach the edge due to the various constraints that are present there. That is why numerous outdated fieldbus protocols are still being employed for this last section. To achieve seamless end-to-end connectivity, it has been necessary to make Ethernet technology fit for purpose at the edge.

SPE’s arrival

Single Pair Ethernet (SPE) technology has signified a major step forward in the progression of Ethernet within the industrial arena. It is a more streamlined version of the Ethernet protocol that can address the requirements of modern industrial systems, including those most notably of the Industrial Internet of Things (IIoT). Rather than needing multiple conductor pairs for transmission, SPE uses echo cancellation to enable support of data transfer via just one conductor pair. This can be done at acceptable speeds and in some cases over relatively long distances. The upshot is that Ethernet compatible cabling can now be attached to IIoT nodes, eliminating the need for inclusion of gateways. While the legacy fieldbus protocols offer poor data rate performance when there are longer transmission distances, SPE has a far better data rate over distance characteristics.

SPE cabling is more lightweight and less bulky than conventional multi-pair Ethernet cabling. Because it is inherently much thinner in diameter, it takes up less space within industrial systems. It is also able to support more acute bending on an ongoing basis – thus increasing the operational lifespan of such cabling when used in production machinery and robotic systems. Its structural simplicity makes it easier to install and will curb the implementation costs involved too.

The evolution of SPE

The initial SPE standard specification was IEEE 802.3bw. This defined full-duplex point-to-point communication at 100Mbps over a distance of 15m. That was followed by other specifications which broadened the scope of scenarios where SPE could be utilised. IEEE 802.3bp-2016 came next, offering faster data rates of 1Gbps over a 15m range, to attend to more data-intensive applications such as those where imaging was involved.

IEEE 802.3cg-2019 was then introduced, comprising two separate PHY specifications. The first of these is 10BASE-T1L, supporting 10Mbps data rates across a 1km reach. This means that edge-based IIoT nodes and associated cabinets situated some distance away can communicate. For the second, referred to as 10BASE-T1S, the objective was to support shorter distances using shared media connectivity. It features a multi-drop approach, where each of the nodes is connected to a single cable segment, thereby avoiding the need for inclusion of a switching device. It is possible for at least 8 nodes to be connected over a 25m mixed link segment. A Physical Layer Collision Avoidance (PLCA) mechanism is incorporated into the specification to prevent packet collision occurring. The multi-drop capabilities of 10BASE-T1S also allow IIoT networks to be expanded, with further nodes being simple to add when required.

Power over Data Line (PoDL) is another aspect of SPE’s evolutionary journey. This is the SPE equivalent of Power over Ethernet (PoE), enabling data signals and electrical current to be simultaneously supplied over the same twisted pair. It is certain to prove invaluable to next generation IIoT network deployments – as only one cable will need to be assigned to any node to cover both of these functions, with cost and space savings thereby being derived. Once a powered device is connected, negotiation is done via the serial communication classification protocol. This determines the power level that is required. 5W can be supplied at 12V or 50W supplied at 48V.

Defining an SPE future

The prospect of Ethernet packets flowing between edge-based equipment and the cloud represents a real game-changer, enabling industrial automation systems to become far more responsive, cost-effective, and adaptable. This finally would get away from having a diverse range of legacy fieldbus protocols that currently remain in use and enable more coherent end-to-end networks to be established. SPE is now making this a reality.

Through the efforts of the different SPE task groups that the IEEE has assigned work to, new specifications will emerge over the coming years. Among these will be longer reach (500m) 100Base T1 and 1000Base T1 capabilities, which are likely to be ready for introduction by 2024 at the latest. Enhancements to 10BASE-T1S are underway that will expand its multi-drop capabilities, so that a larger number of nodes can be supported and extend the distance it can be used over. Further improvements will also be made in relation to PoDL. There are also plans being discussed about the potential of employing hybrid cabling for supplying power in 10BASE-T1S deployments.

Thanks to close collaboration with leading IC suppliers, EBV offers a comprehensive portfolio of semiconductor solutions for SPE implementation and is kept fully updated of these suppliers’ future technology roadmaps. With Broadcom EBV has a supplier in the portfolio that has longest SPE history with the biggest SPE portfolio and the inventor of BroadR-Reach. Customer interested SPE solution can be assured that for all IEEE802.3 SPE Standards PHYs are available. All Automotive products could be used in Industrial and other applications. Automotive parts are already interoperable tested and Switches with integrated T1 PHYs are available.

In addition, through sister company Avnet Abacus, customers are able to access an extensive range of complementary parts like connectors, cables and passive components (e.g. transformer, inductors, capacitors, resistors).
 

EBV’s portfolio of SPE related devices

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About Author

Karl Lehnhoff

Karl Lehnhoff joined EBV Elektronik in 2008 as a regional application manager. From 2011 till 2019 h...

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