INDUSTRIAL


Single Pair Ethernet: The route to finally achieving all-encompassing industrial connectivity


Sara Ghaemi, director technical development at Avnet Abacus, explains how to achieve an effective end-to-end networking infrastructure, based on Ethernet protocols, that will be responsible for much of the digital transformation that is set to happen within the industrial space


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he foundation for more effective industrial automation will be to have communication infrastructure that has a truly end-to-end construction. This means that consistent media must be employed - from the nodes located at the network edge up to the cloud where the acquired information is compiled, stored, and analysed. By having ubiquitous networking media throughout, the need for gateways that otherwise must convert all the different fieldbus protocols at the edge can finally be eliminated. So how can this be achieved?


Industrial Internet of Things (IIoT) is gaining greater traction by the day, helping to make factories and processing plants more efficient and heighten their productivity. Juniper Research predicts that by 2025 there will be approximately 37 billion IIoT nodes in operation, with fellow analyst firm Accenture expecting IIoT to be contributing over $14 trillion annually to the global economy by the end of this decade. These nodes, as well as various other items of industrial equipment, controllers and instrumentation, need connectivity. This can be either wireline or wireless.


Wireless connectivity will not always be the best tactic. Reliability and security concerns can make it impractical. Also, the electro-magnetic interference (EMI) that is commonplace in industrial settings could


prove problematic. On top of this, though wireless arrangements can attend to the data transmission aspect, what if wireline connectivity is still needed to supply power? In such situations, the convenience of a wireless approach would be completely negated, as there would still be the engineering expense of installing and maintaining power cabling to factor in.


Looking at wireline specifically, the advent of Industry 4.0 has driven the implementations of Ethernet connectivity in recent years. Originally intended for enterprise networking, Ethernet has had to evolve in order to address opportunities that have emerged in both the industrial and automotive sectors. Firstly, it needed to become more robust, to cope with the harsh operational environments associated with these applications. Without this, exposure to shocks, vibrations, high humidity, extreme temperatures and thermal cycling could all have an impact on the networks’ operational reliability.


Then there was the need to support deterministic operation, so that safety critical functions could be supported, to ensure that the lives of industrial staff and vehicle occupants would not be jeopardised. The inclusion of time sensitive networking (TSN) protocols was essential here. Despite all of this,


IEEE SPE Specification Data Rate 802.3cg 802.3bw 802.3bp


Table 1: SPE Specifications\ 26 NOVEMBER 2022 | ELECTRONICS TODAY


10Mbit/s 100Mbit/s 1Gbit/s


Distance 1km 50m 15m


the fieldbus protocols already employed in the industrial sector still had certain advantages. This was due to Ethernet in its conventional form being quite bulky and expensive to implement.


Making Ethernet more suitable for the edge


Edge-based hardware does not need availability of large amounts of bandwidth, as the data rates involved are likely to be relatively small for use in monitoring, for example. What it does require is interconnectivity that is cost-effective - due to the long distance that might need to be covered within an industrial facility, or large volumes of nodes that may be incorporated into an IIoT network.


In addition, the interconnects should generally have small physical dimensions, because of the space constraints that are often present within high density industrial systems and the compactness of IIoT hardware. Therefore the next step in the progression of Ethernet technology in an industrial context was to streamline it. This was the motivation behind Single Pair Ethernet (SPE).


Differentiating SPE from conventional Ethernet


Reliance on multiple conductor pairs meant Application Example


General industrial networking/IIoT Process/motion control Machine vision


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