The 2021 ARC Industry Forum Europe focused on “Accelerating Digital Transformation in a Post-COVID World.” The workshop held by the CC-Link Partner Organization CLPA, silver sponsor of the ARC event, summarized the status and benefits of using Time-Sensitive Networking (TSN) in Ethernet based networks, like CC-Link IE TSN. Successful TSN implementation offers benefits for all parties involved, be it automation device suppliers, machine builders or end users. Advantages include simpler network architectures and machine designs, optimized performance, increased productivity, better end product quality, and better integration of OT and IT.
TSN Drivers for Success
ARC associated senior consultant Frank Thomas covered 3 important drivers of success for implementation of TSN:
- The need to handle real-time high-volume data traffic generated by IIoT applications.
- A large enough ecosystem of automation devices offering TSN.
- A successful implementation of TSN generates benefits for all parties involved: automation suppliers, their clients, and end users.
Real-Time High Volume Data Traffic
An example of the real-time high-volume data traffic generated by IIoT applications is the quality control of coins produced by a high-speed coin press. In earlier days, samples were taken out of a certain batch to be examined in a lab. Batches of coins were released to further production process steps only if they met quality criteria. With IIoT, there is now the opportunity to install inline process quality control with video cameras and sensors to measure thickness, diameter, and weight of each coin produced and transfer all data in each stamping cycle to an AI based quality evaluation software. This is how TSN-based Ethernet networks enable such IIoT applications.
Ecosystem of Automation Devices
In an ecosystem of automation devices offering TSN there are 3 levels of communication: a) controller to cloud b) controller to controller and c) controller to field devices. Field devices are of particular importance, as TSN technologies enable the creation of one convergent network within a machine rather than several. For example, Mitsubishi Electric recently introduced a series of servo drives with CC-Link IE TSN network interfaces.
TSN: What, Why and Who
John Browett, General Manager of the CC-Link Partner Association Europe presented a comprehensive overview about TSN under the title “Time-Sensitive Networking – What, Why and Who.”
What Is Time-Sensitive Networking?
The key goal of Industry 4.0 or IIoT is higher transparency resulting in better process management. TSN helps to improve the transparency by increased network convergence on the shopfloor and between the IT and OT level.
The key principles of TSN are based on IEEE 802.1 standards, which allow the implementation of a standard, deterministic Ethernet network that provides a foundation for network convergence. Time synchronization based upon IEEE 802.1AS is of utmost importance to achieve precise control of latency and jitter, as well as predictable network traffic flow. On a TSN network, there are queues of different types and the scheduling of those in time slots is covered in the IEEE 802.1Qbv standard.
Why Is Time-Sensitive Networking Important?
In his presentation, John Browett of CLPA explained a typical use case of a production line including multiple network types handling a variety of control functions and how this can be simplified into a single TSN based network. In the past, separate network topologies have been used for real-time motion control. With TSN, it is now possible to converge to one network with a single transparent architecture from the sensor to the cloud.
Who Is Using Time-Sensitive Networking?
Browett provided two use cases to explain the use and benefits of TSN. The first example covers a case study carried out by the Instrumentation Technology and Economy Institute (ITEI) in Beijing, China for mass customization manufacturing for souvenirs. The MES system in this case governs order handling & tracking, production instructions, quality control, and CNC monitoring, including predictive maintenance and energy management. Stage 1, which is the processing stage, is completed by a robot tended CNC machining center that creates the selected frame shape. Stage 2, the assembly, covers vision assisted robot assembly of frame pieces according to its shape.
This vision system interacts on the TSN network with the MES to confirm order, quality inspection and monitoring, order verification, etc. Stage 2 also includes robot supported packaging of finished frames. Stage 3, the logistics stage, consists of an automated storage and retrieval system (ASRS) with automated guided vehicles (AGVs) for the transfer of raw materials and finished products.
This complex network architecture was gradually converted to a simpler converged network architecture based on CC-Link IE TSN. Mitsubishi Electric is a strategic partner on this project and a CLPA board member. Schaeffler is the condition monitoring supplier on this project and Cognex is the machine vision system supplier.
The other case presented was on the automation of a Lithium-Ion polymer battery production. In the past, a process such as lithium battery manufacturing was based upon different networks – fieldbuses & Ethernet – resulting in a complex network structure with a lack of transparency and difficult network diagnostics. The production line consists of different machinery modules. All automation is based upon Mitsubishi-Electric PLC with multiple servo axis control and integration of robots and HMIs.
The benefits achieved are simpler network architecture, simpler machine design, and better management by improved process transparency.
Browett summarized the benefits delivered by TSN in 4 major categories:
Simpler network architecture/machine design
- High performance motion control, I/O and safety control combined on a single network.
- Open convergent architecture providing a foundation for future integration of TCP/IP Ethernet devices onto the same network.
- Reducing engineering & maintenance costs.
Greater process transparency and better management
- Opportunity to combine process and control data on a single network architecture.
- Better access to data from the process.
- Foundation for AI based maintenance systems to further reduce down time.
- Gigabit bandwidth removes communication bottleneck.
- Supports integration of high speed/accuracy motion control with low-speed status monitoring without compromising performance.
- Leads to reduced cycle times.
Better integration of OT and IT systems
- Connect OT systems to the same network architecture as IT systems.
- Engineering tools and supervisory systems can share one network.
- Improve collection of sensor data, accuracy and improve uptime.
Conclusions and Recommendations
At the end of his presentation on Time-Sensitive Networking Browett wrapped up with following conclusions:
- TSN is a key technology for the future of industrial automation.
- TSN provides simpler network architectures/machine designs.
- TSN provides greater process transparency/better management.
- TSN enables more productivity.
- TSN enables better integration of OT and IT systems.
The session concluded with a panel discussion. The panelists were: Christian Bergdahl, Product Marketing Manager BU Anybus, HMS Networks Group; Chih-Hong Lin, Global Technology Partner Manager, MOXA Europe; Piotr Siwek, FA Deputy Marketing Director EME for Mitsubishi Electric, and Frank Thomas of ARC Advisory Group Europe. Tom Burke from the CC-Link Partner Association Americas moderated the panel discussion.
It was a common understanding of all panelists that today’s OT network infrastructure with its many different network protocols (traditional fieldbuses and/or Ethernet based networks) takes longer engineering and diagnostic time if more than just one network is installed in a manufacturing process.
The different fieldbus standards are not compatible with each other, and that adds to integration and management costs. On the other side, the huge installed brownfield base is a challenge for all automation suppliers to design compatible TSN based network interfaces. It will take some time until a unified, vendor independent, standards based TSN network becomes common in industrial automation. To avoid different incompatible TSN profiles, both IEC and IEEE are jointly working on a new standard to define a TSN profile for industrial automation. Tom Burke emphasized how important it is for the different stakeholders in industrial automation to collaborate.
Typical verticals driving the implementation of TSN network are automotive, food & beverage, life sciences, intralogistics, and data centers. An important aspect of the IT/OT convergence using TSN based Ethernet networks is the time stamp feature, which allows very detailed data analytics.
Vertical applications requiring high volume real-time data communication, high-speed real-time motion control, or even both, benefit greatly from an Ethernet TSN implementation. TSN offers the necessary sensor data acquisition to execute process data analytics. To maximize the benefits of TSN, a sizable ecosystem is important. This applies for TSN to the second layer of the ISO/OSI layer model and includes further OPC UA standard semantics on the top layers.
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Keywords: CC-Link IE TSN, CLPA, Network Convergence, IT/OT Convergence, Process Transparency, Real-Time, Latency, Jitter, Time Synchronization, Scheduling, IIoT, Industry 4.0, ARC Advisory Group.