Time-sensitive networks: what, why and who

Summary

The ARC Industry Forum Europe 2021 focused on “Accelerate digital transformation in a post-COVID world. “The workshop hosted by partner organization CC-Link CLPA, silver sponsor of the ARC event, summarized the status and benefits of using time-sensitive network (TSN) in Ethernet networks, such as CC -Link IE TSN A successful TSN implementation provides benefits to all parties involved, whether they are automation device vendors, machine builders, or end users. Benefits include architectures network and simpler machine designs, improved performance, increased productivity, better end product quality, and better integration of OT and IT.

TSN Success Drivers

ARC Senior Associate Consultant Frank Thomas covered 3 important success factors for TSN implementation:

• The need to manage high volume, real-time data traffic generated by IIoT applications.
• A sufficiently large ecosystem of automation devices offering TSN.
• A successful TSN implementation generates benefits for all parties involved: automation vendors, their customers and end users.

Real-time high volume data traffic

An example of the high volume, real time data traffic generated by IIoT applications is the quality control of parts produced by a high speed coin press. In the past, samples were taken from a certain lot for laboratory examination. Batches of parts were only released for further stages of the production process if they met the quality criteria. With IIoT, it is now possible to install online process quality control with video cameras and sensors to measure the thickness, diameter and weight of each part produced and transfer all data from each stamping cycle to AI-based quality assessment software. This is how TSN-based Ethernet networks enable such IIoT applications.

Automation device ecosystem

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 particularly important because TSN technologies allow the creation of a converged network within one machine rather than several. For example, Mitsubishi Electric recently introduced a series of servo motors with CC-Link IE TSN network interfaces.

TSN: what, why and who

John Browett, Managing Director of the CC-Link Europe Partners Association presented a comprehensive overview of TSN under the title “Time Sensitive Network – What, Why and Who”.

What is a time sensitive network?

The key objective of Industry 4.0 or IIoT is greater transparency resulting in better process management. TSN helps improve transparency by increasing network convergence in the shop floor and between the IT and OT levels.

The key principles of TSN are based on the IEEE 802.1 standards, which enable the implementation of a deterministic standard Ethernet network that provides a basis for network convergence. Time synchronization based on IEEE 802.1AS is of the utmost importance to achieve precise latency and jitter control, as well as predictable network traffic flow. On a TSN network, there are queues of different types and the programming of these in the 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 comprising multiple types of networks handling a variety of control functions and how this can be simplified into a single TSN-based network. In the past, separate network topologies were used for real-time motion control. With TSN, it is now possible to converge to a network with a single architecture transparent from the sensor to the cloud.

Who uses the time sensitive network?

Browett provided two use cases to explain the use and benefits of TSN. The first example covers a case study by the Institute for Instrumentation Technology and Economics (ITEI) in Beijing, China, for manufacturing mass personalization products for souvenirs. The MES system in this case governs the management and tracking of orders, production instructions, quality control and CNC monitoring, including predictive maintenance and energy management. Step 1, which is the processing step, is completed with a robot-tensioned CNC machining center that creates the selected frame shape. Stage 2, assembly, covers the robotic assembly assisted by vision of chassis parts according to its shape.

This vision system interacts on the TSN network with the MES to confirm the order, control and monitor the quality, verify the order, etc. Step 2 also includes robotic packaging of the 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 into a simpler converged network architecture based on CC-Link IE TSN. Mitsubishi Electric is a strategic partner in this project and a member of the CLPA board of directors. Schaeffler is the condition maintenance supplier on this project and Cognex is the machine vision system supplier.

The other case presented concerned the automation of lithium-ion polymer battery production. In the past, a process like manufacturing lithium batteries was based on different networks – fieldbus and Ethernet – resulting in a complex network structure with lack of transparency and difficult network diagnostics. The production line consists of different machine modules. All automation is based on the Mitsubishi-Electric PLC with multiple axis control and integration of robots and HMI.

The advantages obtained are a simpler network architecture, a simpler machine design and better management thanks to better process transparency.

TSN advantages

Browett summarized the benefits TSN provides in 4 main categories:

Simpler network architecture / machine design

• High performance motion control, I / O and safety control combined on a single network.
• Open converged architecture providing a basis for the future integration of Ethernet TCP / IP devices on the same network.
• Reduced engineering and maintenance costs.

Greater transparency of processes and better management

• Possibility of combining process and control data on a single network architecture.
• Better access to process data.
• Foundation for AI-based maintenance systems to further reduce downtime.

More productivity

• Gigabit bandwidth removes communication bottlenecks.
• Supports integration of high speed / precision motion control with low speed condition 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 computer systems.
• Engineering tools and supervision systems can share a single network.
• Improve sensor data collection, accuracy, and improve uptime.

Conclusions and Recommendations

At the end of his presentation on time-sensitive networks, Browett concluded with the following conclusions:

• TSN is a key technology for the future of industrial automation.
• TSN offers simpler network architectures / machine designs.
• TSN offers greater process transparency / better management.
• TSN enables more productivity.
• TSN allows better integration of OT and IT systems.

Round table

The session ended with a round table. The panelists were: Christian Bergdahl, Product Marketing Manager BU Anybus, HMS Networks Group; Chih-Hong Lin, Head of Global Technology Partners, MOXA Europe; Piotr Siwek, Deputy Marketing Director FA 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.

All the panelists understood that today’s OT network infrastructure with its many different network protocols (traditional fieldbus and / or Ethernet-based networks) takes more engineering and diagnostic time if more ‘a network is installed in a manufacturing process.

The different fieldbus standards are not compatible with each other, which increases integration and management costs. On the other hand, the huge base of installed brownfields is a challenge for all automation vendors to design compatible TSN-based network interfaces. It will be some time before a unified, vendor independent, standards-based TSN network becomes mainstream in industrial automation. To avoid different incompatible TSN profiles, the IEC and IEEE are jointly working on a new standard to define a TSN profile for industrial automation. Tom Burke underlined how important it is for the different players in industrial automation to work together.

Typical verticals for TSN network implementation are automotive, agribusiness, life sciences, intralogistics and data centers. An important aspect of IT / OT convergence using TSN-based Ethernet networks is the timestamp feature, which enables very detailed data analysis.

Vertical applications requiring high-volume real-time data communication, high-speed real-time motion control, or even both, benefit greatly from a TSN Ethernet implementation. TSN provides the necessary sensor data acquisition to perform process data analysis. To maximize the benefits of TSN, an important ecosystem is important. This applies for TSN to the second layer of the ISO / OSI layer model and includes additional OPC UA standard semantics on the upper layers.

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Keywords: CC-Link IE TSN, CLPA, Network Convergence, IT / OT Convergence, Process Transparency, Real Time, Latency, Jitter, Time Synchronization, Schedule, IIoT, Industry 4.0, ARC Advisory Group.