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TopIntroduction To Time-Sensitive Network
In the early 1980s, Ethernet has been equally established as a dependable wired solution in both computer and automation networks. The open standard allows terminals to be quickly and simply connected as well as easily scaled to exchange data with relatively inexpensive hardware. Ethernet was, however, not originally designed to meet the requirements posed by automation technology, particularly in regard to guaranteed and real-time communication. Therefore, various bus systems in automation have evolved using Ethernet on a physical level while implementing proprietary real-time protocols on top. These systems often lead to the exclusive use of the network infrastructure as well as vendor dependencies. Today, such networks handling time-critical data traffic are separated from networks directing less-critical data traffic to eliminate reciprocal negative interference. In the future, Industry 4.0 applications will require increasingly more consistent Ethernet networks. Such networks can only be produced at a great cost with the traditional structure. Time-Sensitive Networking (TSN) provides a solution aiming to change these current conditions.
The Traditional Ethernet protocol splits the Information Technology (IT) which primarily focuses on the communication among the devices used in automation and Operational Technology (OT) which uses hardware and software to monitor and control the devices, events, processes, etc. These two domains are focusing on different aspects in the automation sector basically IT on connectivity and OT on availability. Industry 4.0 focuses mainly on connectivity, automation, and communicating real-time data. Industrial automation is going through digital variations to fulfill the requirements of remote access, process automation, data acquisition, and intelligence in manufacturing [Figure 1].
The Industrial and Automation Sector demands hard real-time communication with stringent bounded latency where Traditional buses like Controller Area Network (CAN), and FlexRay can’t support the tremendous growth (Thiele and Ernst, 2016). Since the traditional Ethernet doesn’t have the capability to reserve bandwidth; the industrial experts started developing Ethernet Extensions. As a result, EtherCAT, PROFINET, POWERLINK, etc. were developed and they are capable of providing time-critical data traffic with guaranteed latency with minimal jitter and packet loss.
To integrate the various services, the exemplary automation pyramid is being changed into a broad network, which incorporates sensors associated with higher control levels. The segregation of field and control levels is progressively dissolving, making the requirement for a uniform, converged network in which basic critical data traffic can be transmitted in parallel with non-critical data traffic without degrading the performance. The traditional Ethernet must be changed to meet these requirements and sub-standards are expected to combine data traffic over the existing network infrastructure. Time Sensitive Network (TSN) is one of the standards under IEEE 802.1 and it can be used to control data communication in the form of time synchronization as well as prioritization of data streams. The network's real-time communication capability, reliability, and availability are increased and thus guaranteed.
The key characteristics of TSN include
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Guaranteed latency for time-critical data
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Converged network for handling critical and non-critical data
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Common network infrastructure for higher-layer protocols
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Real-time monitoring and control
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Vendor independent