There are numerous fieldbus standards aimed at ensuring real time support, but none of them provide a manufacturer or platform-agnostic networking solution. An answer has been provided in the form of Time-Sensitive Networking (TSN). Andreas Mangler, Director Strategic Marketing at Rutronik explains more.
Nevertheless, mobile applications using consistent real time communication are possible when combined with 5G. The Fraunhofer Institute for Production Technology (IPT) and a number of mechanical engineering, robotics, and network engineering companies have recognised the potential to combine TSN with 5G.
Together, they have developed a capable communication infrastructure with the aim of creating a high availability, reliable, and secure communications solution for sensors and actuators with cloud support. TSN provides real time communications for wired communication, while 5G cellular technology handles all mobile and cloud connections.
One potential application would be the precise control of a robot and a tool, or of two robots working together during live production. Data processing can be outsourced to the cloud using this infrastructure, with the results sent back to the system.
This enables robots in highly dynamic production systems to be controlled adaptively and flexibly without them needing to be connected directly to one another. This works with devices from a multitude of manufacturers, even using existing machinery and installations.
There are numerous other scenarios that can also benefit from this combination, and some that perhaps may only be feasible with this constellation – among them autonomous driving, transport applications and remote surgery.
TSN for real time Ethernet
Let’s first consider TSN, an evolution of standard Ethernet. Ethernet provides data communication services between devices from different manufacturers for IT purposes, namely in office environments.
Industrial Ethernet is a more robust solution that is suitable for harsh environments. Special protocols such as EtherCAT, Profinet, and Modbus TCP also provide a more deterministic environment – in other words, data packets are transmitted or received at predictable times, and the risk of data loss is eliminated.
However, what Industrial Ethernet does not guarantee is real-time support. To this end, the IEEE 802.1 Task Group has developed a range of sub-standards referred to as Time-Sensitive Networking (TSN).
These standards define protocols for timing and time synchronisation (IEEE 802.1AS) and for the configuration (IEEE 802.1Qcc in particular) and control of data traffic (Traffic Shaping and Scheduling, IEEE 802.1CB, 802.1Qbu, 802.1Qbv among others). This means that there is a common plan that defines when data packets are forwarded in a prioritised fashion.
TSN does not cover all seven layers of the OSI model for network protocols, in which each layer defines how two systems communicate with specific tasks and functions. TSN addresses Layers 1 and 2 and the real time aspect, which covers the entire vertical length of the model.
This means that more protocols are required for the higher layers. Businesses can continue to use their existing standards here, for example OPC UA. TSN provides the benefit of guaranteed real-time support without the need to adapt standards.
Interoperability and IT/OT Convergence
Thanks to open standards, TSN enables manufacturer and platform-agnostic interoperability between different devices, machines, and installations, similar to how standard Ethernet works in office IT.
These standard Ethernet components can be integrated into TSN, allowing TSN to establish a consistent link between IT (information technology) and OT (operational technology) components. Critical and noncritical systems with different traffic classes can operate in the same network.
With bandwidths ranging from 10 Gbit/s to 400 Gbit/s – compared to the 100 Mbit/s commonly seen in Industrial Ethernet networks – TSN also caters to the demands of increasingly large data volumes.
To date, only some of the TSN sub-standards have been ratified – others are still a work-in-progress. Even so, the existing standards can be implemented right away – they already guarantee real time communication and can be adapted to future standards.
Real time support now available wireless thanks to 5G
5G enables real time support to be expanded globally to wireless networks through TSN. 5G enables not only Ultra-Low Latency (ULL) and precise time synchronisation, but also massive increases in reliability, range, and bandwidth compared to its predecessor technologies, all with superior energy efficiency.
5G also enables the creation of private networks that are inaccessible to the public. They provide another substantial boost in performance, data protection, and network security, as well as guaranteed Quality of Service (QoS).
This is how 5G is laying the foundations for secure communication between a variety of machines and installations, robots, and components – ranging from sensors and actuators to cloud services. When developing a TSN network, it is therefore recommended to consider integrating 5G support to ensure that you have a future-proofed, scalable solution.
More detailed information on developing a 5G campus network is provided in the article on page 15SAA.
Integrating 5G into a TSN Network
A concept of the Research Group of the German Research Center for Artificial Intelligence (DFKI), the Technical University of Kaiserslautern, and Nokia Bell Labs shows how TSN time synchronisation (IEEE 802.1AS) can be integrated in compliance with 5G standards (Figure 1).
The 5G system comprises a 5G base station (gNB) and a 5G core network (5GC) as well as multiple end devices (UE). One of these end devices (Reference UE) is connected to the wired TSN network as part of the reference system. This device must support IEEE 802.1AS so that it can be synchronised with the TSN clock via the Grandmaster.
The 5G system also has its own synchronisation mechanism, where each 5G base station (gNB) synchronises the end devices networked with it using the primary (PSS) and secondary (SSS) synchronisation signals.
The end devices use these signals to identify their wireless cell and radio frame; using specific synchronisation algorithms, they can adjust for frequency and time differences. Each incoming System Frame Number (SFN) is also paired with the current time of the reference end device and transmitted to each connected end device. If OPC UA PubSub is used for distribution, all end devices connected to the base station can be synchronised.
The synchronisation between the base station and connected end devices means that only the offset relative to the corresponding TSN time needs to be identified.
Figure 2 offers an illustration of the message layers. The User Datagram Protocol (UDP) in combination with Multicast is used as the transport protocol so that every device in the Multicast group receives the subscribed messages.
As shown by Figure 3, the research team successfully used this arrangement with a synchronisation interval of 31.25 ms to achieve synchronicity of 350 ns between an evaluation kit and an Intel NUC Mini PC.
Conclusion
TSN raises standard Ethernet to a new level of real-time communication. It allows for the consistent and manufacturer-agnostic connection of IT and OT devices. 5G allows this opportunity to be expanded to mobile connections.
Combining both technologies provides the foundations for collaborative robotics and the reliable control of highly dynamic production systems, including mobile robots, and also for goods transport systems, assisted and autonomous driving, remote surgery, and augmented and virtual reality applications.
Figure 1: Concept for distribution of TSN time in a 5G network.
Figure 2: The OPC UA PubSub transport layers for messages.
Figure 3: The maximum offset in synchronization between the TSN evaluation kit and an Intel NUC Mini PC was 350 ns with a synchronization interval of 31.25 ms.
What does real time mean?
To guarantee real time support in a network, the following features are required:
Each device requires a precise internal clock so that each data packet can be timestamped.
All devices in the network need to be time-synchronised.
Data packets are transmitted with very low latency, meaning that they are bound by a very strict time limit. Time-critical applications require ultra-low latency (ULL) of just a few milliseconds or even less than a millisecond, end-to-end—i.e. from the time transmission starts until it has been fully received.
Low jitter: Latency is always related to time variations referred to as “jitter.” Some industrial control applications prohibit jitter from exceeding a few microseconds, while others can handle delays of up to a millisecond.
Jitter and latency are also the most important parameters for the quality of service (QoS) of a ULL network.
Solution Provider for TSN and 5G
All products required to create a TSN and 5G infrastructure are available in Rutronik’s portfolio. Application engineers, product managers, and line managers are on hand to assist with the implementation.
Processors and Boards with TSN Support
Intel’s 10 nm Atom x6000E processor and N- and J-series Pentium and Celeron product ranges have 2.5 GbE MACs with TSN functions integrated. Compared to the previous generation, they have 1.7 times the single-thread performance, up to 1.5 times the multithreading performance, and twice the GPU performance.
The UHD graphics allow for a resolution of up to 4kp60 on up to three displays concurrently. Their Programmable Services Engine (PSE) with an ARM Cortex-M7 microcontroller offers independent processing power with low DMIPs and I/Os for IoT applications. They also feature a network proxy, embedded controller, and sensor hub.
For remote monitoring and administration and for remote firmware and software updates, the processors offer in-band support via WiFi or Ethernet; alternatively, out-of-band administration over wired Ethernet is also possible.
There are numerous boards from a variety of manufacturers available from Rutronik based on these Intel processors. The SMC-93 from Seco is the first SMARC module specially developed for functional safety in safety-critical systems.
Advantech offers a SMARC 2.1 module with up to four cores and 40% better CPU performance as well as improved GPU performance compared to previous models. The SOM-2532’s features include two GbE LAN interfaces for TSN PHY for real time device communication as well as USB 3.2 Gen2 and PCIe Gen3.
With CAN FD, much higher data transfer rates are possible, achieving user data transfer speeds that are ten times faster – an interesting feature for data-rich applications. The WISE-DeviceOn software from Advantech ensures that IoT devices operate with stability and can be conveniently administered remotely. The SOM-2532 is therefore particularly recommended for applications in automation, medical engineering, and transportation.
The MIO-5152 3.5″ SBC (single-board computer) from Advantech is also equipped with the latest Intel processors and Advantech’s WISE-DeviceOn. It comes fitted with 32 GB of DDR4-3200 and offers numerous interfaces, including HDMI 2.0/DP/LVDS, Dual GbE, four USB 3.2 sockets, four USB 2.0 sockets, six UART interfaces and TPM support.
Kontron also offers a SMARC 2.1 module (SMARC-sXEL (E2)), as well as two COM Express models with TSN support (COMe-mEL10 (E2) COM Express mini Type 10 and COMe-cEL6 (E2) COM Express Compact Type 6). All three are available as versions with the Intel Atom x6000E, Pentium, or Celeron, and offer numerous interfaces.
A comparable board with a Thin Mini-ITX form factor is available from DFI and is based on the Intel Atom X6000 series.
Kontron has developed a ready-to-use TSN system – the KBox C-102-2 TSN Starter Kit includes the IPC KBox C-102-2 and the PCIe-0400-TSN Gigabit Ethernet interface card with TSN support.
The four network interfaces with switching function are based on standard Ethernet as specified by IEEE 802.3 and make it possible to develop deterministic control applications in convergent networks from OT to IT without the need for additional switches.
The system is shipped with Real time Linux and a network management tool for rapid setup of a TSN network. Upgradeable hardware and software open up the solution for new and evolved TSN standards.
The target applications include deterministic industrial control computers and servers, convergent networks for critical and noncritical traffic, and security solutions to protect deterministic traffic against malicious attacks.
5G Cards, Modems, and Antennas
The Rutronik product portfolio also includes a selection of hardware components for developing a 5G campus network, including 5G cards and modems as well as antennas. This includes one of the world’s first available 5G solutions – the FN980 5G-M.2 card from Telit, which supports LTE and 5G sub-6GHz bands worldwide.
With a form factor of 30x50mm and a temperature range of -40 to +85°C, it is also suitable for use in industrial applications. The FN980m model also supports the new mmWave frequency bands above 30GHz. Telit’s cards are based on the Snapdragon X55 5G chipset from Qualcomm, as are the 5G-M.2 modules of the AIW-355 family from Advantech.
Unlike Telit, however, Advantech is gearing towards specific versions for Europe, North America, and Japan with the AIW-355 range. At 30x52mm, it has a slightly larger form factor, and a reduced temperature range of –10°C to +55°C. The 5G-M.2 cards from both manufacturers have multiple 5G and GNSS antenna sockets.
Rutronik offers various 5G antennas from 2J, AVX, and PulseLarsen. The compact W3415 5G SMD antenna from PulseLarsen supports all sub-6 GHz bands (4G and 5G), and measures just 40×7×3mm.
The W3554 series ultra-wideband dipolar antenna from PulseLarsen with a frequency spectrum of 698 to 6,000MHz is suitable for 5G applications and for 2G, 3G, 4G, GNSS, WiFi, Bluetooth, Bluetooth Low Energy, Zigbee, and the 868, 915, 2,400, and 5,000MHz ISM bands. The PCB antenna measures just 30x120x0.2mm.
For developing an internal campus network, Rutronik also supplies special 5G network components from FSP. These are suitable for supplying base stations, access networks, data centers, or individual network devices.
Whether for 5G, 4G, 3G, or 2G, with support for GNSS, WiFi, Bluetooth, and more, the W3554 ultra-wideband dipolar antenna from PulseLarsen can do it all.
