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Industrial Ethernet Book 104

33 IEEE Time Sensitive Networking deterministic Ethernet standards TSN enables real-time communication over IEEE standard Ethernet. This network platform and high-quality scheduling tools, will help companies in the fields of industrial automation, transportation and energy production realize the commercial value of integrating real-time systems into the Internet of Things. MORE THAN TEN YEARS AGO, TTTech started a research program to answer the question as to whether it would be possible to provide real-time and safety capabilities over Ethernet, in a way that is fully compatible with IEEE 802 Ethernet standards. Based on the company’s expertise in time-triggered and scheduled networks, a solution was developed and evolved over time. The solution first appeared as Time-Triggered Ethernet, and was designed in to NASA’s Orion project in the mid 2000’s. The Orion spacecraft, with TTTech technology on board, was successfully launched into space in 2014. In the decade since it was first developed, Time-Triggered Ethernet has been standardized as SAE AS6802 and used as a deterministic communication protocol in a range of aerospace, automotive, and industrial controls applications. Today, a Deterministic Ethernet solution integrates SAE AS6802 along with IEEE 802.1 AVB (Audio-Video Bridging) and the emerging IEEE 802.1 TSN (Time-Sensitive Networking) standards. This article focuses on TSN, and its constituent sub-standards, giving an overview of TSN technology, its applications and the advantages of using it. Real-Time Ethernet Ethernet technology has proven incredibly successful and is a near ubiquitous method of communication in the IT world. It is a very well standardized and open technology that is easily accessible to everyone, provides a wide range of bandwidth and physical layer options, and has significant support in a diverse range of application areas. Up until now there has been no real- time support in IEEE standardized Ethernet, leading to a number of proprietary modifications of Ethernet being used in industrial and transportation systems where real-time communication is a critical requirement. These solutions have typically been developed for specific tasks or domains, for example, Profinet, EtherCAT and Ethernet/IP which compete for recognition in industrial automation. While these protocols perform their specialized tasks capably, they have limits when it comes to combining with standard (classical) Ethernet networks and devices. The scalability of adapted Ethernet solutions for different industries is also limited as each is tailored for a specific application area. For this reason the IEEE Time-Sensitive Networking task group has been working since 2012 on standardizing real-time functionality in Ethernet. TSN (Time-Sensitive Networking) is the set of IEEE 802 Ethernet sub-standards that are defined by the IEEE TSN task group. The new standards describe several mechanisms for improved or even guaranteed real-time delivery of Ethernet traffic. Most prominently, TSN defines the first IEEE standard for time-triggered message forwarding in a switched Ethernet network, and therefore fully deterministic real-time communication within the 802 suite of standards. TSN achieves deterministic real-time communication over Ethernet by using global time and a schedule which is created for message paths across multiple network components. By defining queues which transmit their messages based on a time schedule, TSN ensures a bounded maximum latency for scheduled traffic through switched networks. In control applications with strict deterministic requirements, such as those found in automotive and industrial domains, TSN offers a way to send time-critical traffic over a standard Ethernet infrastructure. This enables the convergence of all traffic classes and multiple applications in one network. Advantages of TSN Industrial applications such as machine control, robotics, power generation, process control and transportation all require real-time communication to perform safely and securely. To ensure that this critical requirement is met, industrial systems have typically either implemented modified Ethernet variants or dedicated standard Ethernet networks running in parallel. Now, industrial systems are expanding out from small closed networks to an Industrial Internet of Things, where reliable, converged, remote, secure access to all network components is needed. Limited Ethernet access will no longer suffice for customers wishing to incorporate IoT concepts into their industrial systems to increase productivity, increase up-time or reduce maintenance. TSN supports both industrial control and IoT connectivity needs, enabling industrial real-time systems to benefit from techniques such as remote system management and 2.2018 industrial ethernet book SOURCE: TTTECH Technology MQTT decouples devices from applications and reduces bandwidth usage. Devices connect directly to a MOM, or the MQTT server, where data is gathered.


Industrial Ethernet Book 104
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