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reaction – and low jitter – the variation in delay time of received packets of information.Mechanisms are

needed for distributed coordination – the collision- avoidance and time synchronisation strategy specified in the IEEE 802.11 basedWLANstandard. In the past, fulfilling these requirements resulted in non- standard network infrastructure or unconnected standard networks where devices and data are not accessible throughout the infrastructure. TSNwill open up critical control applications such

as robot control, drive control and vision systems to the Industrial Internet. This connectivity then enables customers, suppliers and vendors tomore readily access data and to apply preventativemaintenance and optimisation routines to these systems. It is envisioned that TSNwill be useful in a range

of applications, including in addition to manufacturing, utilities, transport and oil & gas. To address these needs of IIoT all the way to the

control system, the IEEE 802 standards group has been adding new capabilities to the Ethernet and wireless standard to enable it to support time sensitive networking, which will allow standard IT traffic to converge with time-sensitive control traffic. Other standards bodies to note are the AVnu

Alliance and the Industrial Internet Consortium (IIC). The former covers certification for TSN-based Ethernet while the latter develops “the standards, best practices and processes of the Industrial Internet” to help simplifymulti-vendor systems targeted at vertical applications; it also hosts testbeds. OPCUA TSNis the proposed unified standard for

industrial automation and IIoT connectivity, and the participating companies intend to supportOPCUA TSNin their future products.OPCUA TSNis the combination of enhancedOPCUA Publisher/ Subscriber (Pub/Sub) technology with the IEEE TSN Ethernet standards. It provides all of the open, standard building blocks required to unify communication for industrial automation and it enables the broad convergence of information technology (IT) and operation technology (OT) that is fundamental to realising the IIoT and Industrie 4.0. The technology will be used to support real time

control and synchronisation of high-performance machines over a single, standard Ethernet network, withmulti-vendor interoperability and integration. First pilots of these products are already being

integrated in an IIC testbed. The group’s objective is to show compatible controller-to-controller communication between devices fromdifferent


The testbed is designed to demonstrate how to do the following:  Combine different critical control traffic (such as OPC UA) and best-effort traffic flows on a single, resilient network based on IEEE 802.1 TSN standards  Demonstrate TSN’s real time capability and vendor interoperability using standard,

converged Ethernet  Assess the security value of TSN and provide feedback on the ability to secure initial TSN functions  Show ability for the IIoT to incorporate high-performance and latency-sensitive applications  Deliver integration points for smart real time edge cloud control systems into IIoT infrastructure and application

20 /// Environmental Engineering /// February 2017 WHAT IS A TIME-SENSITIVE NETWORK?

By defining queues based on time, time-sensitive networking ensures a boundedmaximumlatency for traffic through switched networks. This means, says TTTech Computertechnik AG, standard Ethernet will now allow:  Message latency guaranteed through switched networks  Critical and non-critical traffic converged in one network

‘ TSN will

open up critical control applications such as robot control, drive control and vision systems to the Industrial Internet

 Higher layer protocols sharing the network infrastructure  Real time control extended away from the operations area  Sub-systems more easily integrated  Components added without network or equipment alterations  Network faults diagnosed and repaired faster

vendors usingOPCUA TSNover standard IT infrastructure.Other companies that share this common vision of unified communication between industrial controllers and the cloud are welcome to join and contribute to this collaboration. The testbed shows the value of the technology as

well as some of the challenges in implementations froma number of vendors. It will not only document some of the value, but will also provide feedback to the relevant standards organisations on areas of further clarification or improvement. “Testbeds are amajor focus and activity of the IIC

and itsmembers.Our testbeds are where the innovation and opportunities of the Industrial Internet – new technologies, applications, products, services and processes – can be initiated, thought through and rigorously tested to ascertain their usefulness and viability before coming tomarket,” saysDr Richard Soley, executive director of the IIC. Member participantNational Instruments (NI) is

hosting the testbed. Speaking atNIDays 2016, Sacha Emery, senior systems engineer (ATE) atNational InstrumentsUK, covered themain elements needed to support time sensitive networking: time synchronisation, traffic scheduling and system configuration. Customers that want to access the technology platformcan join theNI Community “Time SensitiveNetworks.” In coordination with Cisco and Intel,NI has

announced that there is to be an Early Access Technology Release to support TSN. This involves two newNI parts (cRIO-9035 and cRIO-9039, featuring Intel Atomprocessors and the Intel i210 TSN-enabledNIC), TSNsoftware and a Cisco switch (to cover the IT piece), with under 100ns comms between CompactRIOcontrollers on the network and deterministic comms over standard Ethernet. This will enable customers to build distributed

systems that performsynchronised I/O, code execution and deterministic communication for distributed control andmeasurement loops, all using standard Ethernet. These controllers use LabVIEW systemdesign software tomaintain synchronised time to the network and expose that time to code running on the real time processor, as well as the code running on the FPGA. LabVIEWis already designed with time as a core concept, whichmakes it simple for users to tightly coordinate signal processing, control algorithms and I/Otiming with scheduled network transmission and betweenmultiple systems distributed across a network. EE

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