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DATA NETWORKS


Industrial systems deal with mission-critical data that must be transferred and shared within strict bounds of latency and reliability. Important messages must not be held up by idle network chat! Can Ethernet step up to the plate? Andy Pye investigates


Time sensitive Ethernet controls critical data


biggest difference being time sensitivity. Manufacturing operations require tight


A Standard


coordination of sensing and actuation to safely and efficiently performclosed loop control. Industrial automation approaches have traditionally been differentiated and separated fromone another by different incompatible and non-interoperable standards used for communication between devices. As a result, customers have often found themselves locked into proprietary systems, while vendors have had to developmultiple versions of the same product. Recognising the inadequacy ofmost network


infrastructures for handling such time-sensitive data, industrial suppliers, IT vendors and electronics makers are collaborating to update the standard Ethernet protocol to a next-generation Ethernet standard called time-sensitive networking (TSN). A group of big automation players – ABB, Bosch Rexroth, B&R, CISCO, General Electric, KUKA, NI,


IEEE TIME SENSITIVE NETWORKS OVERVIEW Area


Title


IEEE 802.1ASrev, IEEE 1588 Timing & synchronisation Enhancements & performance improvements IEEE 802.1Qbu & IEEE 802.3br Forwarding & queuing IEEE 802.1Qbv IEEE 802.1Qca IEEE 802.1Qcc IEEE 802.1Qci IEEE 802.1CB …


Frame pre-emption Forwarding & queuing Enhancements for scheduled traffic


Path control & reservation Path control & reservation Systemconfiguration


Enhancements & performance improvements


Time-based ingress policing Per-streamfiltering & policing Seamless redundancy Additional projects


Frame replication & elimination for reliability Continual evolution of the standard


s we scale to a world of billions of intelligent, connected devices, crucial differences are emerging between the Internet of Things (IoT) and its subset, the Industrial Internet of Things (IIoT). The


 Early access technology provides testbed capability for new standards on time sensitive networks


ParkerHannifin, Schneider Electric, SEW- EURODRIVE and TTTech – have started an open technical collaboration under the umbrella of the Industrial Internet Consortium(IIC) and the OPC Foundation. This group is aiming for open, unified, standards-based and interoperable IIoT for deterministic and real time peer-to-peer communication between industrial controllers and the cloud. Based on open standards, this will enable devices fromdifferent vendors to be fully interoperable. TSNis an attempt to answer some of the


challenges for the transmission of large amounts of data deterministically. It enables a standard, single, open network infrastructure, supportingmulti- vendor interoperability, with real time control and synchronisation of high-performancemachines over a single, standard Ethernet network. It is under development by the Time-Sensitive


Network TaskGroup (IEEE 802.1), an initiative created by the Institute of Electrical and Electronics Engineers (IEEE). Precise time synchronisation for 802.1AS, deploys the IEEE 1588 Precision Time Protocol to support synchronisation ofmultiple data streams; and to combine time synchronisation with trafficmanagement to deliver latency guarantees – thismeans each switch identifies time-critical data packets and puts themin a special queue. They are forwarded at specific times to create a network flow between the talkers and listeners across the network.


SOME DEFINITIONS Support of fast control applicationsmeans the network needs to support communications with low latency – the time delay between an action and a


February 2017 /// Environmental Engineering /// 19





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