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Industrial Ethernet Book Issue 101 / 22
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PoE, PoE++, PoDL: enhancements to IEEE 802.3

The IoT is exploding with applications in automotive, home automation, building automation, and machine-to-machine. While Ethernet has become the universal communications network, the current status of cabling standards such as IEC/SC65C/JWG10, ISO/IECJTC1/SC25/WG3 and ANSI TIA/TR42 is vitally important.

THE IEEE 802.3 COMMITTEES RECENTLY published a higher level PoE (PoE++) and Power over Data link (PoDL), in addition to a focus on the status of IEEE 802.3 adaptions of standard Ethernet and the opportunities that it presents. These new powered enhancements can provide an attractive solution for powering a range of small devices, up to larger IO devices.

PoE++ is attractive for industrial applications as it potentially can deliver some 90+ watts to the Powered Device (PD). Even more exciting are the number of newly proposed high speed single pair Ethernet adaptions being defined. These new adaptions will simplify the wiring and reduce space needed for the cabling in industrial installations.

The national and international cabling standards are already actively engaged with IEEE 802.3 working groups helping to define the cabling requirements for these new emerging networks. We will discuss the new industrial channel definitions (E2E Links) being defined by ISO/IEC that promise to help our customers successfully install and test their cabling.


This diagram shows the interconnection between standards documents and organizations. Work within one group can have a ripple effect, and the committees end up working together to create a complete system.

Standardization of cabling

Standardization of cabling systems for communications networks has been ongoing since the early 90s. Since the initial standardization of industrial cabling systems, there have been many new high performance components and enhancements proposed. The standards organizations continue to work to provide standardization of these new components and systems.

There are several national and international cabling standards that have a direct impact on networks throughout the world. These standards are either based on ODVA network standards and/or are the foundation for the ODVA networks. For example, Industrial Ethernet was first defined in ODVA and was based on TIA cabling standards. Subsequent releases of the TIA cabling standard included a variant of the ODVA industrial Ethernet standard.

The figure on this page shows a relational map of the national and international standards organizations. The work within the individual standards committees is precipitated by a cause and effect relationship of one or more standards or consortia. Developments within any one of these standards bodies can cause ripple effect for the other standards. An abstract example is a request for a new Ethernet channel to be created in IEC/SC65C/JWG10 that creates work for ISO/IEC/JTC1/WG3 and ripples to ODVA and TIA. The originating request could come from anyone of the 21+ consortia around the world.

The standards committees are tightly linked and work together to create a complete system. Most of the connections are through Experts and Liaisons working between the committees. The component definitions provide technology to the cabling committees, and then the installation committees.

The root of many of the industrial Ethernet enhancements comes from the enabling work of IEEE 802.3. The cabling standards work together with IEEE802.3 and with other national and international cabling standards to publish a comprehensive set of standards taking the audience from the design and planning phase to the installation and verification/certification phase of a network infrastructure.

Using the well-used adage "Ethernet to the edge", we find that there are many changes to the standards. For example, adding 1000Base-T applications to industrial has caused new connectors to emerge (M12-8 X-coding). New cables are emerging in support of industrial 1000Base-T as well.

IEEE 802.3

Over the past 15 years, these standards have continued to evolve and expand. In the recent two years, IEEE 802.3 have added two new Ethernet networks/applications and are in the process of adding two new Ethernet networks/ applications.

These new networks are aimed at expanding Ethernet into new spaces and application areas. For example, one of the most exciting applications are three, unshielded or shielded single pair physical layers, 1000Mb, 100Mb and 10 Mb.

IEEE 802.3bp (1000BaseT1) was published June, 2016 featuring 1000Mb/s over a single pair cable either shielded or unshielded cable. 802.3bp has two different lengths and environments. Link segment type A is referenced as Automotive and total length is 15 meters. Link segment type B is referenced as Industrial and the total length is 40 meters. 802.3bp will require a new PHY for the physical layer of the OSI model.

IEEE 802.3bw (100BaseT1) was published October, 2015 offering 100Mb/s over a single pair cable either shielded or unshielded cable. 802.3bw was developed for both automotive and industrial environments, and provides overall length up to 15 meters. 802.3bw will require a new PHY for the physical layer of the OSI model.

IEEE 802.3cg (10BaseT1) is looking to be published late 2018. IEEE 802.3cg is for the 10Mb and will focus on industrial and building automation as their primary customers. This network has the potential of providing channel lengths of 1000 meters (10X that of any other IEEE defined Ethernet application). 802.3cg will require a new PHY for the physical layer of the OSI model, allowing up to 10 inline connectors for the 1000 meters.

All three new applications have the potential to provide power to the communications channel to the device. IEEE 802.3bu Power over Data Link (PoDL) was published October, 2016. IEEE 802.3bu defines the power insertion, detection, and extraction scheme to serve all three of the single pair applications. The detection methods of voltage/current configurations used for 2 and 4 pair Ethernet networks will be used in these three applications with some modification to the protocol.

The three single pair networks fit well with the direction of industrial Ethernet in that they will open doors to sensor/actuator level Ethernet enabled devices. As copper costs continue to fluctuate in the market place the need to reduce copper content in the cabling will become more important. In addition as the need to provide smaller devices increases, reduced connector and PHY designs can help with PCB space. The estimated PCB board space savings of a single pair Physical Layer is about 55%.

Single pair applications

In addition to single pair applications, one other application worth mentioning that has future use in industrial, is the recently published IEEE 802.3bz, September 2016.

As part of the long term migration strategy, 2.5G and 5G physical layers might have a place in industrial. The bandwidth needs of industrial still do not match the aggregate needs of a campus sized back bone. However, there are two factors to consider for the future, high bandwidth devices such as vision and the migration of devices from non-Ethernet based networks onto the industrial Ethernet control network. This migration may create a need for a mid-bandwidth backbone.

Why 2.5/5G over 10G, the answer is in cost and power requirements. While 10G is becoming more popular, it comes at a high cost and high power needs. In harsh environments, power is heat.

ISO/IEC/JTC1/SC25C/WG3

We have already discussed the enhancements in IEEE 802.3, so now our focus is on the enhancements to ISO/IEC/JTC1/SC25C/ WG3. This committee is responsible for the international standardization of generic cabling. The well-known standard, ISO/ IEC 11801 is currently being redrafted as a comprehensive standard in 6 initial parts. The important highlights of this work are the incorporation of the industrial standard ISO/IEC 24702: 2006 in to part 3 of ISO/ IEC11801. The MICE concept, originally a Technical Report (ISO/IEC TR29106:2007) will be integrated into ISO/IEC/11801. This is very important as this takes the informative nature of the MICE concept and makes it normative.

In a parallel development is the creation of a new channel called "End 2 End Link". This new channel has several reference implementations that are very similar to a normal channel of 1 to 4 connections.

However, the main difference is that it includes the performance of the two end plugs of the channel. This new channel came at the request of the industrial installation committee within IEC/SC65C/JWG10. Here we saw a need to help the customers identify potential connection installation issues at the two ends of a channel.

Primarily to the benefit of our industrial customers who choose to build their systems "in place" through the use of field installable connector options. The approach is to define a whole set of new limit lines that include the performance of the connections at the end of the channel in the definition and test limits. Following the final release, it is expected that field testers will have the ability to measure and detect performance problems up to the customer equipment interfaces. The estimated release time for both ISO/ IEC11801 and TR 11801-9902 is late 2017. There are discussions within the committee about including the End-2-End Link Technical Report (ISO/IEC 11801-9902) into the release of ISO/IEC 11801.

IEC

The current stability date of the installation standards is 2018. That seems a long way off, but the work has already begun to create the new editions of the standards. This collection of installation standards consists of one umbrella standard, IEC 61918 and 21 consortia standards (profiles) IEC 61784-5-n (n = 1 to 21). Each consortia have its own profile number. For example, ODVA networks are found in IEC 61784-5-2.

Due to the expansion of Ethernet, the national and international standards and the set of installation standards must be updated. Most of the profiles are at edition 2 revision level and will be re-released at edition 3 in 2018. This year, two new Ethernet based industrial profiles were added. The 2018 release will include the End-2-End Link definitions and new connectors supporting 1gigabit sealed connectivity. In addition, it expected that the performance requirements of 1gigabit channels will be included. This input will come from TIA and ODVA and is based on research performed on 1gigabit channels in high noise environments.

ANSI/TIA

ANSI/TIA is a national standardization committee consisting of many sub groups. Within sub group 42, there are approximately 16 subcommittees. Subcommittee 42.9 is responsible for publishing the industrial cabling standard. The current revision level of this standard is ANSI/TIA 1005-A. The most recent addition to this standard was the M12-8 X-coding sealed connector for harsh areas supporting data rates up to 1 gigabits. Currently, there is a void in the area of cable specifications to support 1 gigabit channels. A draft addendum is currently being reviewed for these new cable specifications.

Another draft addendum that TIA 42.9 is reviewing is for the requirements for incorporating of IEEE 802.3bp in the industrial environment that includes connector requirements. In addition, it is expected that future releases of this standard will include End-2-End Link definitions defined by ISO/IEC/ JTC1/SC25C/WG3.

Bob Lounsbury, Principal Engineer, Rockwell Automation and Brad Woodman, Engineering Manager, Molex.


Source: Industrial Ethernet Book Issue 101 / 22
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