What does time-sensitive networking and real-time Ethernet data mean for the future of industrial systems?
Avnu Alliance members explain how real-time communications enabled by Time Sensitive Networking (TSN) will strengthen the future of industrial systems.
The Industrial Internet of Things (IIoT) brings the opportunity to create smart systems that share data between devices across the enterprise and in the cloud. As interest in IIoT and Industrie 4.0 continues to grow, more designers, engineers, and end-users are looking to Time Sensitive Networking (TSN)—a set of standards under revision from the Institute of Electrical and Electronics Engineers (IEEE)—to solve the need to process raw data in a timely fashion, reduce latency, increase robustness, and provide a foundation for more advanced manufacturing and product models where data can be more flexible and shared between layers of the control system. (The TSN Work Group, part of the IEEE 802.1 Working Group [Ethernet], evolved from the Audio Video Bridging [AVB] Work Group.)
To support these new capabilities of an IIoT infrastructure and to connect network devices, there is a need for an interoperable system that allows multiple manufacturers, protocols, and organizations to share the same TSN network. To prepare for this, Avnu Alliance selects and certifies a set of underlying mechanisms to meet a given market's requirements, creating a common infrastructure that others can build on to enable convergence between operational technology (OT) and information technology (IT). This convergence increases connectivity to industrial devices and enables a faster path to new business opportunities including Big Data analytics and smart, connected systems and machines.
Avnu Alliance is an industry partnershipthat fosters and develops an ecosystem of manufacturers providing interoperable devices for industrial networked systems. The industrial segment within Avnu includes member companies across the entire ecosystem and supply chain including IT vendors, silicon providers and industrial suppliers all working together to create an interoperable ecosystem of low-latency, time-synchronized, highly reliable networked devices. Avnu creates certification programs to ensure interoperability of networked devices for multiple markets and applications from machine control, health care, smart grid and robotics to power generation and process control, as well as automotive for the future of autonomous driving. Each of these areas employ embedded processing to perform closed-loop autonomous control, have high availability requirements, and are highly software defined.
Control Engineering (CE) caught up with several Avnu Alliance members to ask how the IIoT is affecting industrial networks and what TSN means for the future of industrial systems. Todd Walter is chief marketing manager, National Instruments and Avnu Industrial Segment chair; Ludwig Leurs is director of Ethernet convergence at Bosch Rexroth; Anil Kumar is principal systems engineer of the Internet of Things group at Intel; Paul Brooks is business development manager at Rockwell Automation; Bogdan Tenea is product specialist at Ixia; and Paul Didier is industry solutions architect at Cisco.
CE: How has the evolution of Ethernet changed the approach to designing industrial control systems?
Ludwig Leurs: Standard Ethernet has evolved to enable next generation control systems. With this, recent work by IEEE 802 LAN/MAN Standards Committee (LMSC), the Internet Engineering Task Force (IETF), and other standards groups has extended the ability to operate time-sensitive systems over standard Ethernet networks, supporting diverse applications and markets including professional audio/video, automotive, and industrial. These standards, driven primarily by the IEEE 802.1 TSN task group, define new mechanisms for creating distributed, synchronized, real-time systems using standard Ethernet technologies that will allow convergence of low-latency control traffic and standard Ethernet traffic on the same network.
TSN supports real-time control and synchronization, for example, between motion applications and robots, over one Ethernet network. TSN can at the same time support other common traffic found in manufacturing applications, driving convergence between IT and operational technologies. TSN is not a disruptive technology, it enables existing industrial real-time control applications to coexist and interoperate, such as the new OPC UA publisher/subscriber model currently being finalized in the OPC Foundation. As Avnu has shown success in audio/video applications, it will be helpful being able to reuse this technology in modern machines using video cameras in control loops.
As TSN supporting network infrastructures become more prevalent, we will see that many of today's modified Ethernet networks can move to TSN-based networks using their OT-based application layers on standard 802.1 Ethernet.
CE: With networks becoming increasingly congested with IIoT data, how does TSN ensure that data gets communicated to make IIoT viable to help users?
Anil Kumar: TSN promises a world of smarter, hyper-connected devices, and infrastructure. Manufacturing machines, transportation systems, and the electrical grid will be outfitted with embedded sensing, processing, control and analysis capabilities. Though much of the data collected by industrial sensors and control systems in an IIoT application are not time-sensitive, there will also be a great deal of mission-critical, time-sensitive data that must be transferred and shared within strict bounds of latency and reliability.
Requirements of TSN such as a common clock for transmission scheduling, latency provisions, reserved bandwidth and redundancy make it so that TSN ensures precise time synchronization to support synchronization of multiple data streams. Large data sets from machine vision, 3-D scanning, and power analysis can put a strain on network bandwidth. TSN will support full-duplex standard Ethernet with higher bandwidth options such as 1 Gb, 10 Gb, and even the 400 Gb version in IEEE 802.3. It also offers top-tier IT security provisions and interoperability with scalability that can grow into large systems. TSN can also integrate with existing brownfield applications and standard IT traffic and is future-proof, as it is constantly evolving.
CE: How will the new generation of Ethernet with TSN features improve over previous generations of the standard?
Paul Brooks: TSN's value is derived from simplifying convergence and increased connectivity, unlocking the critical data needed to achieve the IIoT promise of improved operations driven by Big Data analytics. Designers can take advantage of the advancements in processing, communications, software, and system design originating from the consumer world with a standard that evolves while providing precise timing.
For industrial markets specifically, these standards support the ability to simplify development and deployment of distributed, synchronized, control systems commonly found in a variety of industrial applications including machine control, factory automation, power generation and distribution, oil and gas exploration, etc. Many of today's generation of control applications are deployed using nonstandard network interfaces and infrastructure. Limitations to Ethernet have caused a fragmentation and lead to the creation of variants of Ethernet that include real-time performance to meet the needs of measurement and control applications.
These variants often modify hardware and infrastructure components of the Ethernet stack to provide guarantees on behavior. These modifications provide the latency and bandwidth reservations needed for control. However, because they required modification of hardware they are no longer interoperable with standard Ethernet, and they are much harder to access on the network, if at all. Additionally, in some cases the modifications prevent the systems from evolving along with Ethernet standards, and they become limited in bandwidth compared to standard Ethernet.
Unlike the proprietary modified variants of Ethernet, TSN and related efforts, including IETF projects such as DetNet [deterministic networking], provide mechanisms to expand solutions to these applications using standard Ethernet technologies in a manner that enables convergence between OT and IT data on a common physical network. TSN ensures the predictable delivery of time-critical traffic and has the potential to integrate with existing applications as well as standard IT traffic to strengthen interoperability. Other advantages include simplified development and faster time to market.
CE: How are Avnu Alliance and its members driving this next-generation standard?
Todd Walter: Avnu Alliance is a nonprofit member run organization promoting, educating, and enabling companies to create devices that provide reliable, synchronized deterministic networks. Our focus is the creation of an open, interoperable ecosystem through interoperability verification and testing across broad markets. As the capabilities to Ethernet are updated with new standards, Avnu Alliance provides the community to discuss, collaborate, certify, and promote the continually evolving network capabilities that enable the convergence between OT and IT.
Avnu Alliance is made up of key technology and equipment providers including leading silicon suppliers such as Intel and Analog Devices; network infrastructure vendors such as Cisco and Belden Hirshmann; end-station suppliers such as National Instruments, Rockwell Automation, and Bosch Rexroth; and test equipment providers such as Ixia and Sprient. By covering all levels of the value chain and markets including industrial, automotive, and professional AV [audio/video], we are able to effectively create a common, global foundation across all markets.
To promote the shared network and accelerate products to market, Avnu facilitates a common technical platform through a number of services including open-source software, hardware reference designs, test plans, and certification services to develop and verify the correct operation and implementation of TSN-enabled products.
Avnu Alliance also coordinates with other organizations such as IEEE, IETF, ODVA, OPC-UA and Industrial Internet Consortium (IIC) with the goal of creating this common foundation allowing multiple protocols and manufacturers to coexist on the same TSN network. Avnu also has made it a priority to educate other groups on TSN, which has led to the development of liaisons, where various groups can benefit from shared knowledge, which then contributes to a broad and growing membership.
Avnu has collaborated with the IIC to develop the world's first TSN testbed to showcase the value to the standards and the ecosystem of manufacturing applications, including the ability for IIoT to incorporate high-performance and latency-sensitive applications. We are hosting the testbed at National Instruments.
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