Single Pair Ethernet - Standardization landscape
With Single Pair Ethernet, a new physical layer is entering the world of Ethernet communication. Born out of the automotive industry, SPE is also developing into a key technology for the coming steps of digitization in industrial automation. Ethernet IP can finally be transmitted continuously from the cloud to the field level via just one pair of copper wires.
In industry, communication protocols and the infrastructure are subject to strict rules. To ensure interoperability and interchangeability, standardization is a high priority. This also applies to Single Pair Ethernet.
This article shows the work of international committees, the current status of standardization around the new physical layer SPE, and explains to users how and with which standards the path to the IIoT will be successfully taken.
SPE Standards base
The following organizations and committees are relevant for SPE standardization and work very closely together in a lively exchange to create the coordinated set of standards. The SPE Industrial Partner Network actively participates in the committee work through its members.
• IEEE 802.3 – Transmission method, MDI, link segment
• IEC SC46C – Symmetrical copper cables (IEC 61156-x series)
• IEC SC 48B – Connectors (IEC 63171-x series)
• ISO/IEC JTC 1/SC 25/WG3 – Universal wiring (ISO/IEC 11801 series)
• IEC SC65C – Industrial networks, cabling (IEC 61918 und IEC 61784-5 series)
• ANSI/TIA TR-42 – Cabling systems (valid for North America)
INTERACTION OF STANDARDS ORGANIZATIONS:
IEEE802.3 specifies the primary transmission method and must also define the transmission channel, such as the transmission length and number of connectors. The cabling Application note: Single Pair Ethernet - standards landscape ISO/IEC and TIA consider the transmission channel and refer to the corresponding IEC groups for the cable and connector specification with regard to the connectors and cables. There is close cooperation between IEEE802.3 and ISO/IEC and TIA.
IEEE 802.3 Ethernet Protocols
This diagram shows the published SPE protocols with their associated possible transmission lengths and essential details.
Except for 10BASE-T1S (not shown graphically) all SPE protocols are point to point (P2P) protocols like the "classical" Ethernet protocols. These are also compatible with the Power over DataLine (PoDL) remote power supply technology. The 10BASE-T1S standard is a point to multipoint (P2MP) or as IEEE802.3 calls it, a MultiDrop transmission system and thus works like an Ethernet bus over a minimum 25 m unshielded cable with a minimum of 8 devices. PoDL cannot be used here at present. The IEEE802.3da working group wants to increase the change and the number of bus nodes to at least 16 nodes and the transmission length to at least 50 meters.
Due to the focus on in-vehicle applications, all SPE standards, with the exception of IEEE 802.3cg, do not specify specific MDI connectors. This allows users in the automotive industry in particular to use manufacturer-specific connectors.
IEEE 802.3cg was adopted in November 2019 and there the LC Style according to IEC 63171-1 and the T1 Industrial according to IEC 63171-6 are listed as optional MDI (wording: "...may be used..." = "can be used"). Other connectors, especially special types for automotive, or also PCB terminals are possible, provided they meet the defined requirements. However, for cabling in buildings, data centers and industry, the connectors selected in the ISO/IEC 11801 and TIA sets of standards are LC Style according to IEC 63171-1 and the T1 Industrial according to IEC 63171-6.
In March 2021, at the IEEE802 - Plenary Meeting, a working group was formed to extend the point-to-point protocols to add TSN functionality for 10BASE-T1L and to look at possible increases in transmission lengths. Furthermore, the IEEE802.3cy working group is working on SPE speeds above 10Gbps. Results in the form of approved standards for all these working groups are expected from 2023 to 2025, depending on the working group (See also: www.ieee802.org/3/index.html).
IEC 61156-x – STANDARDIZATION OF SPE CABLES
Within the IEC working group SC46C for the standardization of data cables by the meter, there are the following standards projects:
• IEC 61156-11 – SPE data cables up to 600 MHz bandwidth for fixed installation (edition 1 published)
• IEC 61156-12 – SPE data cables up to 600 MHz bandwidth for flexible installation (edition 1 published)
• IEC 61156-13 – SPE data cables up to 20 MHz bandwidth for fixed installation (CD available and publication of edition 1 planned for 07/2022)
• IEC 61156-14 – SPE data cables up to 20 MHz bandwidth for flexible installation (planned)
IEC 63171 – STANDARDIZATION SPE CONNECTION TECHNOLOGY
The first SPE connector standard draft was already submitted by HARTING to SC48B in 2016 and published as IEC 61076-3-125 to CD document. In 2017, another SPE connector draft was submitted for standardization by CommScope and it was decided to create the common IEC 63171 series of standards for all SPE connectors. Accordingly, the PT63171 project team was established at SC48B and tasked with creating this new series of standards. The standards already in progress up to this point were completed as self-contained documents and later integrated into this new series of standards in the course of revisions. The following standards projects have already been published or are still in progress:
• IEC 63171 – Basic standard with all specifications and test sequences (Edition 1 published)
• IEC 63171-1 – CommScope SPE connector based on LC interlock for M1I1C1E1 applications (Edition 1 released and Edition 2 launched)
• IEC 63171-2 – SPE connectors from Reichle & De-Massari for M1I1C1E1 applications (FDIS approved and publication in preparation)
• IEC 63171-3 – SPE connector from Siemon based on a pair of the well-known Tera connector for M1I1C1E1 applications (withdrawn)
• IEC 63171-4 – SPE connectors from BKS for M1I1C1E1 applications (CD available)
• IEC 63171-5 – SPE connectors from Phoenix Contact based on IEC 63171-2 mating face for M2I2C2E2 and M3I3C3E3 applications (second CDV in preparation)
• IEC 63171-6 (previously IEC 61076-3-125) - SPE connectors from HARTING and TE Connectivity for M1I1C1E1, M2I2C2E2 and M3I3C3E3 applications (Published in January 2020 and Edition 2 in progress)
Note: IEC 63171-1 (LC Style) and IEC 63171-6 (Industrial Style) are complete standard documents with all necessary specifications and test sequences. All standards started later refer to the basic IEC 63171 standard and only include the different mechanical designs.
The IEC 63171-6 for T1 Industrial is the first available standard for SPE connectors worldwide and includes versions from IP20 to IP 65/67.
sPE CABLING STANDARDS
SPE and the connectors standardized for it flow into the current cabling standards. Internationally, this applies above all to the series of standards for structured cabling according to ISO/IEC 11801: 2017 (Edition 3) and, in a similar way, to the European series of standards in CENELEC according to EN 50173, where SPE was first incorporated into Part 3 Industrial Cabling via annexes (amendments). The central document for these annexes is ISO/IEC 11801 TR9906 "TECHNICAL REPORT: Balanced 1-pair cabling channels up to 600 MHz". The implementation of SPE in the ISO/IEC 11801 documents is so important because only this standard describes the cabling channels with all the necessary parameters (length, number of connections, bandwidth and the complete set of transmission parameters including NEXT, FEXT, shielding characteristics, etc.) in relation to the environment - MICE - and can therefore also be verified by measurement after installation.
ISO/IEC 11801-3 AMD1 was published in April 2021. This new annex includes the SPE cabling channels:
• For industrial applications including the 10 Mbit/s 1000 m channel and the 1 Gbit/s 40 m channel in Annex E (normative) "Requirements for 1-pair cabling channels up to 600 MHz"
• and specifications for End-to-End Link (E2EL) up to 500 MHz / Cat.6A in Annex D (normative) "Requirements for End-to-End Link configurations".
In parallel, the installation standards for industry as a basis for the cabling of automation solutions according to IEC 61918 (IEC SC65C) are also being adapted accordingly. To this end, work is being done on the addition of SPE to IEC 61918 Edition 4 AMD1. The publication is planned for 03/2022. To what extent this will then influence the automation profiles themselves remains to be seen. What is certain is that PI (with PROFINET according to IEC 61784-5-3) and ODVA (with EtherNet/IP™ according to IEC 61784-5-2) are actively involved in the further development and implementation of standards for SPE and are developing corresponding profile-specific standard documents. A similar approach will certainly be taken with Advance Physical Layer (APL), based on 10BASE-T1L, for the process industry, and a new profile will also be developed for this in IEC 61784-5-x.
In conjunction with the component standards for connectors and cables, all users for SPE receive clear guidelines for the construction and testing of corresponding transmission links.
For the time being, these cabling systems are limited to a range of 40 m for 1 GBit/s SPE. For the 10 Mbit/s variant, ranges of 1,000 m and beyond will be realized.
Other papers on SPE cabling relevant to the U.S. including Canada and Mexico, such as ANSI/TIA-568.5, are being prepared at TIA TR 42.9. In the TIA 42.9 papers this is realized via a revision: ANSI/TIA-1005-B (industrial cabling without SPE). In terms of content, all these supplements are largely congruent.
These cabling standards provide the user with information on the structure of the cabling, the cabling components to be used to achieve the performance specifications and the limit values for checking the cabling. Thus, they are the most important tool for the construction and commissioning of SPE cabling systems. At the same time, they ensure compatibility between devices and cabling via the references to the component standards (e.g. connectors according to IEC 63171-6). This compatibility is a basic requirement for the function of networks and connections based on SPE and thus the basis for IoT/IIoT. The use of other cabling components is possible in principle, but then no longer compliant with the standard and carries the risk of incompatibilities and functional losses.
INTERNATIONAL COORDINATION FOR A UNIFORM STANDARD
For this reason, ISO/IEC JTC 1/SC 25/WG 3 and TIA 42 started international selection processes at the beginning of 2018 to define uniform interfaces. These two selection processes were co-initiated by IEEE 802.3, which requested a recommendation for an SPE MDI (= Media Depended Interface, the SPE device interface) from ISO/IEC and TIA.
More than 20 national IEC expert committees participated in this selection process. As a result of this selection, two mating faces prevailed:
• for building cabling (M1I1C1E1) the mating face according to IEC 63171-1: this mating face is based on the proposal of the company CommScope;
• for industry and industry-related applications (M2I2C2E2 and M3I3C3E3) the mating face according to IEC 63171-6: this mating face is based on the proposal of HARTING with the "T1 Industrial".
The selection process at TIA 42 has confirmed the results of ISO/IEC and thus there is clear global agreement on the SPE interfaces. These selected mating faces are now being incorporated into the respective international cabling standards. IEEE 802.3 has also specified these SPE interfaces in IEEE 802.3cg as the recommended Media Depended Interface (MDI).
This ensures the prerequisite for the large-scale use and thus for the successful marketing of SPE technology with the consistent compatibility of devices, cables and connectors in different fields of application and creates planning security for all market participants.
MICE describes environmental conditions for installations and provides planners and users with valuable information for specifying technical equipment and cabling. Requirements for mechanical robustness (M), IPxx degree (I), chemical and climatic resistance (C) and electromagnetic safety (E) are described. In the broadest sense, M1I1C1E1 describes an environment such as that found in an office building and M3I3C3E3 describes a fairly extreme environment such as that found in industry or outdoors.
OUTLOOK - INDUSTRIAL ETHERNNET USER GROUPS
In addition to the completion of the cabling standards at ISO/IEC and TIA, the focus of SPE standardization will now be on the integration of SPE into the Industrial Ethernet standardization groups such as PI (PROFINET International), ETG (EtherCAT), IDA (Modbus), CLPA (CC-Link IE), ODVA (EtherNet/IP™) and other user groups.
However, depending on the strategic orientation and skill of these user groups, the implementation of SPE in the individual automation profiles will probably be more from the device side (sensor/actuator networks) and will not automatically affect communication in the automation network above. Fast Ethernet (e.g. PROFINET) and Gigabit Ethernet (e.g. EtherNet/IP™) will still predominate here for the time being.
The T1 Industrial according to IEC 63171-6 is set in IEEE 802.3 as MDI as well as in the cabling standards at ISO/IEC and TIA. This makes the T1 Industrial the world's first and only standardized connector for SPE, giving users the assurance of using the right interface for all industrial applications. This comprehensive standardization and referencing of the T1 Industrial makes it the only consistently standardized SPE interface on the market worldwide.
ABOUT THESPE INDUSTRIAL PARTNER NETWORK
The potential of SPE is clear, but the broad rollout of SPE requires work and expertise from a wide range of stakeholders. The SPE Industrial Partner Network was founded by companies with focus in all areas of the SPE ecosystem and advocacy of Single Pair Ethernet. The network works together to ensure that SPE technology is pushed further and faster.
The network provides a reliable platform for all necessary technical experts to cooperate and work together easily over the borders of single companies. Partnerships within the network allow for increases in product and performance variations as well as smoother standardization processes. The founding members of the SPE Industrial Partner Network include HARTING, TE Connectivity, HIROSE, Würth Elektronik, LEONI, Murrelektronik, and Softing IT Networks. Currently, the network has grown up to more than 45 member companies and is increasing weekly.