An Easy Way to Start Working in the New GenerationEthernet: Time-Sensitive Networking (TSN)RELYUM Team∗∗https://relyum.com

ABSTRACT The digital factory demands interoperability and simplicity in communications. TSN is the newgeneration Ethernet designed expressly to meet those requirements. Although the introduction of TSN will beprogressive depending on the sector, some critical ones like Railway or Aerospace, are adopting TSN as thestandard IT/OT network in their new platforms.In this paper, an intelligent TSN NIC card is presented. It embeds all the complexity required to connect astandard PC to a TSN network without the need of installing any special software on the host. This approachenables the use of typical Industrial applications and software under TSN, such as SCADA, MES, OPC (UA),MTConnect, etc.

KEYWORDS

TSNPCNICPCIeSCADADigital Factory

WHERE DO WE WANT TO GO, WHAT IS THE FI-NAL GOAL?

In the automation and digitalization of industry, stagethat was labeled as Industry 3.0, a pyramidal topo-logy of interconnection between the production andmanagement means was defined. Figure 1 shows the

pyramid according to this scheme. At the base, the pro-ductive means, usually controlled by PLCs defining theinput and output logic, are located. At a higher level,receiving information from these media, the SCADAand the industrial MES production management soft-ware are situated. At the highest point of the pyramid,the ERP-type global resource management softwareplans the overall business operative.

The evolution of the digitalization process, basedon the massive use of the "data", aims to obtain gre-ater productivity thanks to a thorough knowledge ofthe product and production. The globalization of thisdigitalization in the industry is forcing the intercon-nection of operating networks (Operational Technolo-gies - OT) and data networks (Information Technolo-gies - IT) through gateway technologies. The techno-logies deployed in both worlds, OT and IT, have beentypically quite different and generally not interopera-ble. This mismatching has generated the emergence ofa plethora of heterogeneous equipment confirming anarea called brownfield.

The OT/IT integration roadmap does not end in thisintermediate situation. Instead, it raises the adoption

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by SoCe

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Figure 1 The Pyramid of Automation (Industry 3.0).

of a communication technology at the link level that isvalid for both worlds. In this way, it would be feasiblean all-to-all data exchange topology in a homogeneousplant, similar to a pillar as shown in Figure 2. At thebase of this pillar, next to the productive means, a Dis-tributed control based structure is placed. These areinput and output elements with a certain level of in-telligence and communication capacity. This structure,called Field I/O, interfaces with powerful computingand communication Edge Computing equipment andwith local servers. This combination builds the LocalCloud.

In this Pillar context, the traditional layer-based com-munication and cybersecurity scheme in no longer va-lid. The elements included in the Field I/O wouldcommunicate directly with applications and servicesenabled in remote Cloud, as can be seen in Figure 2.

This Pillar requires a single interconnection networkfor OT and IT. It is the so-called Factory Backbone. But,to move from theory to practice, a valid communica-tion technology is necessary to support the real-timebehavioral of the OT traffic and the large bandwidthdemanded by IT applications. Additionally, it must besecure and preferably, interoperable, standardized andlicense-free. Is there a valid proposal?

INTRODUCTION TO TIME-SENSITIVE NETWOR-KING

Since 1983 where the solution for local computer net-works was standardized as Ethernet (6), it has evolvedfrom the technical and application point of view. Alt-hough its original use was oriented to networks of localcomputers, Ethernet has been extended to many othersectors. In fact, it has become the de-facto standard forfield buses. It stands out for its massive application inthe Industry (Profinet, Ethernet IP, Ethercat, Sercos III,etc.), Electric Sector (high- availability Ethernet for IEC61850 (5)) or Automotive (7).

The diverse proprietary solutions based on Ether-net that have emerged in the past have solved one ofthe key shortcomings of Ethernet in its original ver-sion: the lack of real-time communication support.Thanks to the application of these proprietary solu-tions, the need for deterministic behaviors in OT hasbeen covered. However, the lack of interpretabilityamong the solutions of different manufacturers haslimited the capacity of the end-user to evolve freelytowards a unique infrastructure for computing andnetworking. Therefore, in the aforementioned sectors,vendor-independent standardized technical solutionswith ensured long lifetimes in the market are deman-ded. The development of technologies covering these

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On-premises Automation Cloud

Cyber Physical Production Systems Distributed Control unit merges PLC & IO Modules

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Increased Interaction

Centralised Supervision

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Increase of device numbers

ML/IA Microservices

ML/ IA

Figure 2 The Pillar in Industry 4.0. Graph based on (4).

demands would provide a significant reduction in thecost of equipment and in maintenance effort. Additi-onally, the integration effort of data analysis servicesand industrial software like Machine Learning, MESor ERP would be drastically simplified.

In this sense, the set of IEEE standards defined bythe Time-Sensitive Networking Task Group (8) offersdeterministic communication services on IEEE 802.This set of standards is commercially known as Time-Sensitive Networking (TSN).TSN is a comprehensiveproposal for a single Ethernet-based solution. The ori-ginal AVB working group has been renamed IEEE TSNTask Group, which is in charge of the development ofall standards related to TSN.

The fundamental basis on which TSN is based isthe so-called Time-Aware Shaper. This mechanism hasbeen designed to separate the communication in theEthernet network in repetitive cycles of fixed duration.These cycles are divided into temporary windows ac-cording to the TSN configuration agreed by the nodesthat compose the network. It is possible to configureand assign to each time window one or more Ether-

net priorities of the eight available. The details of theoperation of the Time-Aware Shaper are defined in theIEEE 802.1Qbv standard (2).

Taking into account this discrimination capacity,three fundamental types of traffic are defined: Schedu-led traffic, Best-effort traffic and Reserved traffic. Sche-duled traffic is appropriate for messages with strictreal-time requirements, while Best-effort traffic is madeup of general-purpose messages that do not requireQuality-of-Service functionalities in addition to stan-dard Ethernet. Messages assigned to different timewindows with a reservation of bandwidth set for eachpriority type are considered Reserved traffic. This spe-cific bandwidth reservation capacity is very useful forinformation with soft real-time requirements, such asvideo streams. Figure 3 shows a basic temporal dia-gram of TSN communication. In this case, each Cycleis composed by 2 Slots. The Scheduled traffic is assig-ned to the first one, while the Best-effort traffic andthe Reserved traffic coexist in the second one. Typi-cal configurations require 8 Slots per cycle what offersversatility enough for the definition of detailed QoS

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Figure 3 Distribution in time windows (Slots) according to the type of TSN traffic.

parameters for each data stream.The Time-Aware Shaper allows to define the num-

ber of temporary windows present in each cycle, theirduration and the type of traffic that can be transmitted.Thanks to this mode of operation, Scheduled traffic hasdedicated windows to guarantee the deterministic be-havior of the communication of the real-time messages.Best-effort traffic is accommodated in the rest of thetemporary windows of each operation cycle. One ofthe most important improvements in prioritizing andoptimizing the use of bandwidth in TSN is the use ofthe Credit Based Shaper, as specified in IEEE 802.1Qav(1).

This functionality enables the management of Re-served traffic, which increases the priority of the de-signated traffic, making it a higher priority than Best-effort traffic and of lower priority compared to Sche-duled traffic. The challenge of providing temporarysynchronization in the nanosecond range between allthe devices that make up the TSN network is addres-sed through the use of the IEEE 1588 synchronizationprotocol (9). Thanks to the precision provided by thistechnology, it is possible to control the delay introdu-ced through the network and to have a deterministicEthernet solution based on temporary events. The spe-cific IEEE 1588 profile used in TSN is the IEEE 1588AS-rev (3).

HOW CAN I START TO EVOLVE?

In order to facilitate access to this technology and toallow seamless TSN connectivity to legacy PC systems,

has developed a TSN NIC card pluggable inany Windows or Linux PC. This board embodies all thetechnical complexity of this communication by offeringa standard network interface for communication on

the PC.

Figure 4 RELY-TSN-PCIe NIC card.

This card is represented in Figure 4. It integratesa 4-port SoCe TSN Bridge. SoCe has developed TSNtechnology for the new generation of FPGAs and recon-figurable SoCs (13). Also, SoCe TSN solution has beenembedded in end-equipment for the industrial sector(14), in TSN testing equipment and in railway systems.This bridge implementation offers 2 external ports thatallow attaching copper or fiber optic SFP modules. Ad-ditionally, 2 internal ports enable communication withthe host (PC, server, IPC, etc.) and with the internalCPU of the card. This CPU embedded on the boardmanages the TSN communication and the synchroniza-tion. The software running on this board is accessiblefrom any WEB browser running on the host PC. Thisapproach allows configuring and monitoring the sta-tus of the Network without the need of running anyspecial software on the PC. RELY-TSN-PCIe supportsautomatic configuration using YANG models as defi-

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ned in the standard. However, in order to facilitatethe implementation of early pilots, the board allowsmanual TSN configuration. As an example, the snaps-hot represented in Figure 5 shows the way to assignmanually each traffic priority to each slot.

Figure 5 Manual Time Aware Shaper configurationin the the GUI.

TSN, SOFTWARE APPLICATIONS AND OPERA-TING SYSTEMS...

Depending on the requirements imposed by each ap-plication, it would be necessary to maintain a differentlevel of accuracy in the synchronization of the clockof the host PC. In the same way, the ability to controlthe determinism in the flow of information betweenthe network and the software could be necessary. Forexample, a virtual PLC service in charge of a roboticcontrol would require accessing to real-time data (Sche-duled Traffic) within the strict time limits set by thecontrol loop data. Nevertheless, a SCADA software ismore lax in synchronization requirements demandingin most of the cases a time base in the microsecondsrange, enough to manage the processes under supervi-sion. Therefore, it is necessary to analyze for each casewhat technologies should be integrated to meet the re-quirements and, in turn, not increasing unnecessarilythe complexity of the overall solution. In this sense,

offers two lines of integration of its TSN cards.On the one hand, the use of these boards plugged

into Linux OS computers. In these cases, the globalsynchronization of applications, network and systemsis feasible. Additionally, the traffic management andthe real-time behavioral provided by some patches arepossible at the operating system level. Thus a large

field of experimentation and the capability of globalintegration of services are opened.

And on the other hand, offers support for se-amless integration of these cards in equipment baseson different versions of the Windows OS. In these sce-narios, the card is seen by the OS as a standard NICcard with multiple VLAN based virtual interfaces. Theidentification of the traffic that the card must manage,such as Scheduled, Reserved or Best-Effort, is donethrough the native VLAN markup. The synchroniza-tion is transferred to the operating system by meansof NTP, widely supported by Windows and which cantherefore be used by the applications installed on ittransparently. Other alternatives, such as the use ofPTP stacks in Windows environments and the integra-tion of real-time middleware, can also be addressed inthese projects if required.

Some application examples for these TSN-capablePCs provided with RELY-TSN-PCIe cards are theSCADA applications and machine interconnection. Inthis sense, MTConnect offers a good way to buildmulti-vendor set-ups (10). The MTConnect standardoffers a semantic vocabulary for manufacturing teamsto provide structured and contextualized data withoutproprietary format. MTConnect is used by a largenumber of manufacturers of industrial equipment tofacilitate the interconnection of their equipment withthe IT structure. To do this, they offer the softwareadapter modules called Adapters that work on theirequipment (12). The MTConnect technology groupsthe information received from the adapters through anagent (Agent) (11). The information published by anagent can be processed by IT applications and even beviewed directly through a Web browser (Browser).

Figure 6 represents the set-up of experimentationdeveloped. The PC1 computer hosts the MTCon-nect Agent. This Agent card receives the informationsent from the Adapters installed in the PC2 computerthrough the RELY-TSN-PCIe . The card is responsiblefor managing the distribution of traffic in the corre-sponding Slots according to the selected configuration.In order to facilitate the experimentation, the Adapterssimulators provided in the GIT of the project can beused in such a way that it is not necessary to have thereal machines.

IN SUMMARY. . .

Industry 4.0 evolution demands interoperability andsimplicity in communications. TSN is the new genera-tion Ethernet designed expressly to meet those requi-

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TSN Factory Backbone

MTCONNECT ADAPTER

SIM. 2

MTCONNECT ADAPTER

SIM. 1

WEB BROWSER

MTCONNECT AGENT

WEB BROWSER

PC 2 PC 1

Figure 6 RELY-TSN-PCIe test setup.

rements. The introduction of TSN in each sector andapplication will be progressive. However, some criticalsectors, such as Railway or Aerospace, are showinggreat interest on TSN.

is committed to providing the technology ne-cessary to evolve towards the next generation commu-nication networks in the way that best suits their cus-tomers’ needs. In this sense, the RELY-TSN-PCIe cardand its evaluation kit are an excellent way to get star-ted with technology that, in the medium term, willsimplify the network infrastructure and really enablethe coexistence of OT and IT.

has born to provide innovative solutionsfor networking, synchronization and cybersecurity incritical systems. If you want to receive more detailedinformation about the solutions presented in this paperor any additional inquiry, do not hesitate to contact usat info@relyum.com.

REFERENCES

[1] 2009 IEEE Standard for Local and MetropolitanArea Networks—Virtual Bridged Local Area Net-works - Amendment: Forwarding and QueuingEnhancements for Time-Sensitive Streams.http://www.ieee802.org/1/pages/802.1av.html.

[2] 2016 Standard for Local and Metropolitan AreaNetworks-Media Access Control (MAC) Brid-ges and Virtual Bridged Local Area Networks

Amendment: Enhancements for Scheduled Traffic.http://www.ieee802.org/1/pages/802.1bv.html.

[3] 2018 P802.1AS-Rev Timing and Synchro-nization for Time-Sensitive Applications.https://1.ieee802.org/tsn/802-1as-rev/.

[4] Hummen, R., 2017 What is tsn? a lookat its role in future ethernet networks.https://www.belden.com/blog/industrial-ethernet/what-is-tsn-a-look-at-its-role-in-future-ethernet-networks.

[5] (IEC), N. E. C., 2016 IEC 62439-3:2016, Industrialcommunication networks: High availability au-tomation networks Part 3: Parallel RedundancyProtocol (PRP) and High-availability Seamless Re-dundancy (HSR). http://www.iec.ch/.

[6] IEEE 802.3 ETHERNET WORKINGGROUP, 2018 IEEE 802.3 ETHERNET.http://www.ieee802.org/3/.

[7] IEEE 802.3 Multi-Gig Automotive Ethernet PHYTask Force, 2018 IEEE 1588-2008 - IEEE Standardfor a Precision Clock Synchronization Protocol forNetworked Measurement and Control Systems.IEEE 802.3 Multi-Gig Automotive Ethernet PHYTask Force.

[8] IEEE Time Sensitive Networking TaskGroup, 2018 IEEE 802.1 Standards.http://www.ieee802.org/1/pages/tsn.html.

[9] Institute of Electrical and Electronics Engineers(IEEE), 2008 IEEE 1588-2008 - IEEE Standard for

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a Precision Clock Synchronization Protocol forNetworked Measurement and Control Systems.https://www.smartgrid.gov/document/ieee_1588_2008_ieee_standard_precision_clock_synchronization_protocol_networked_measurement.

[10] MTConnect Institute, 2019a Mtconnect,a free, open standard for the factory.https://www.mtconnect.org/.

[11] MTConnect Institute, 2019b MTCon-nect C++ Agent Version 1.4.0.0, Afree, open standard for the factory.https://github.com/mtconnect/cppagent/.

[12] Relyum, 2019 MTConnect Adapters List- 2019 (Manufacturers and Protocols).https://www.relyum.com/web/2018/09/01/mtconnect-adapters-list-2019-manufacturers-and-protocols/,.

[13] System-on-Chip engineering S.L., 2018a Mul-tiport TSN Switch IP. http://soc-e.com/mtsn-multiport-tsn-switch-ip-core/.

[14] System-on-Chip engineering S.L., 2018b Wago plctsn use-case. https://soc-e.com/wago-unveils-its-new-time-sensitive-networking-controller-for-automationtsn-powered-by-soc-e/.

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