In the foreseeable future, the unbroken trend towards digitalization and networking will affect all areas of industry, transportation and building technology. The cyber-physical system (CPS) enables the connection of information in the form of software with electromechanical components. To implement a CPS, a powerful and robust data infrastructure is required, which can be realized via Ethernet technology in accordance with IEEE 802.3.

What's behind the technology

Table 1: The Ethernet IEEE 802.3 standards for the industrial sector.

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Since the publication of the first Ethernet standard 10BASE-T in the 1990s by IEEE 802.3, Ethernet technology has developed rapidly. The first Ethernet CAT 5 cables in accordance with TIA-568 A/B with a transmission rate of 100 Mbit/s came onto the market as early as 1995, followed by the 1000BASE-T standard in 1999. Today, 1,000 MHz cables in accordance with IEC 61156-5/-6 for 10GBASE-T are state of the art in the cable industry.

The IEC (International Electrotechnical Commission) and its affiliated national standardization committees are developing uniform standards for components, devices and system requirements in line with the technological development of Ethernet technology, which is mainly driven by the IEEE (Institute of Electrical and Electronics Engineers) and TIA (Telecommunications Industry Association) organizations. Time Sensitive Networking (TSN) in accordance with IEEE 802.1 and IEEE 802.3 makes it possible to transmit time-critical and business-critical information with defined response times and accelerates the use of Ethernet technology in industrial environments. The option of using Power over DataLine (PoDL) to transmit data and power via a single-pair data line, which is now specified for different power classes via IEEE 802.3bu and IEEE 802.3cg standards (currently up to 52 W, Power Class 15 according to IEEE 802.3cg), extends the benefits and application possibilities of Ethernet technology. With regard to the IEEE 802.3 specifications, there are a large number of system and product standards for SPE that have been developed and published by the IEC standardization committees:

• IEC 61156-11; -12, -13, -14 (NP) for 1-pair cables
• IEC 63171-1; -2; -4; -5; -6; -7; Connectors for 1-pair data transmission
• ISO/IEC 11801-1 & -3; generic cabling; requirements
• ISO/IEC TR 11801-9906; generic cabling; balanced 1-pair channels up to 600 MHz
• ISO/IEC TS 29125 AMD 1; requirements for remote powering of terminal equipment
• IEC 61918 ED4.0; Installation of communication networks in industrial buildings

Single pair Ethernet connectors are required to connect the SPE cables to the end devices. In order to meet the different requirements in office and industrial environments, connector variants must be selected in accordance with the environmental classifications specified in ISO/IEC TR 29106. IEC 61918 Edition 4.0 contains additional requirements for the 1-pair infrastructure.

Specifications in the fieldbus organizations

The future infrastructure for IIOT: The control level in particular is divided into decentralized control units directly in the field and virtual controllers in the cloud.

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The definition of the specifications for Single Pair Ethernet in the user organizations such as PI, ODVA and OPCF is well advanced. As soon as this work has been completed, the specifications of the user organizations will be included in the corresponding parts of the IEC 61784-5 Fieldbus Profiles series of standards.

The specifications for Ethernet-APL, which were jointly created by the user organizations PI, ODVA, OPC Foundation and FieldComm Group, are already available. Ethernet-APL also uses 1-pair Ethernet technology, which enables both communication at 10 Mbit/s and the power supply of devices. Ethernet-APL supports Ethernet-based protocols and is primarily intended for connecting field devices, mainly for use in hazardous areas in the process industry, to an automation network. The length of an APL trunk segment can be up to 1,000 m. The advantage of Ethernet APL is that the existing fieldbus cable infrastructure can continue to be used. The cable used is a type A fieldbus cable, which is specified in IEC 61158-2. The Ethernet-APL engineering guideline describes the basic system requirements for Ethernet-APL. Single Pair Ethernet technology is being continuously developed with regard to higher data rates, transmission distances and performance classes with the aim of offering the user further application options for this new technology.

Change in the automation pyramid

SPE overcomes the dividing line to the field level, field buses will disappear in the long term.

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SPE is a key technology for transferring information from the field level to the cloud in a decentralized manner with the required bandwidth. SPE is an Ethernet-based technology that is robust enough to be used in the immediate vicinity of value-adding processes under high levels of physical or electromagnetic stress. At the same time, SPE offers a significantly higher transmission bandwidth and complete consistency of the communication infrastructure and protocols from the sensor to the (on-premise) cloud compared to the fieldbuses often used here. This enables further value-added processes such as comprehensive data analysis of manufacturing processes or modern measures to protect against cyber attacks.