NETWORKING & COMMUNICATION FEATURE
Time-Sensitive Networking: How will this benefit an Industry 4.0 environment?
Offering benefits to the interconnected smart factory, CLPA’s CC-Link IE has adopted Time-Sensitive Networking (TSN)
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utting-edge machines, robots and sensors are growing in importance in today’s
manufacturing environment, driven by the demands of Industry 4.0. The interconnected Smart Factory that results from this, however, is driving demand for networking technologies. Machinery and equipment is being used
to improve industrial processes through automation, communications and self- optimisation. To do so, large volumes of data need to be gathered from a broad range of operational technology (OT) systems, processed efficiently – ideally via edge computing, and then transmitted to top floor IT infrastructures. As a result, Smart Factories need a networking technology that does more than handling increasingly greater data traffic. What is needed is a network that can bridge
IT and OT, that can prioritise any time-critical control messaging, as well as assign bandwidth in a faster, more controlled and accurate manner. This, however, can be challenging for most of the industrial Ethernet networks currently available. In particular, within the field level, traditional industrial Ethernet networks often use bandwidth hungry overprovisioning approaches to transfer both time-critical and non-urgent data. They may also work on non-standard ‘Best
Effort’ data delivery systems to optimise determinism. These use Class of Service (CoS) mechanisms to guarantee Best Effort bounded end-to-end latency of time-sensitive data traffic. However, CoS could also be responsible for the delay of urgent process data, with time-critical messages assigned to a queue and not prioritised.
TIME-SENSITIVE NETWORKING (TSN) TSN technology offers an Ethernet standard that implements deterministic capabilities on an ISO/OSI (International Standards Organization/Open Systems Interconnection) Data Link Layer. More precisely, the Institute of Electrical and Electronics Engineers (IEEE) standards 802.1 governing TSN functionalities defines a number of traffic shaping and scheduling tools that guarantee the efficient delivery of any kind of data on an Ethernet network. A key element, defined in IEEE 802.1Qbv, is
TSN’s Time-Aware Scheduler (TAS). This is a gate driver that prioritises Ethernet frames on the basis of their transmission time. When urgent cyclic data need to be transferred, TAS temporarily interrupts the transmission of
and connectivity needs of Industry 4.0, such as openness and interconnectivity, is essential for Phoenix Contact, which is why the company has chosen to rely on CC-Link IE. The biggest advantage of CC-Link IE, explains
Jan Aulenberg, product manager – Industrial Network Technology at Phoenix Contact, is that it is based on the Industrial Ethernet technology standard that is accepted worldwide – meaning it can be used universally. As a result, Phoenix Contact not only
non-urgent traffic. Time-sensitive data can therefore be delivered within the reserved time slots for high-priority traffic. IEE802.1Qbv also specifies a length-aware scheduling mechanism to optimise bandwidth usage. When the scheduler receives a message that needs to be transmitted, the overall length of the frame is checked. If the frame can fit without affecting high priority traffic, the scheduler sends this information. If not, the message is queued or, as defined by IEEE 802.1Qbu and IEEE 802.3br, can be transmitted into two separate parts (frame pre-emption). Thanks to these different IEEE 802.1 sub-standards and tools, TSN can enhance the reliability of traditional industrial Ethernet protocols, and tailor both bandwidth and latency based on the specific application requirements. Consequently, critical and non-critical data traffic can efficiently coexist.
INTERCONNECTION CC-Link IE has adopted TSN, with the resulting solution, CC-Link IE TSN, combining a well- developed open Ethernet framework with Gigabit bandwidth along with the added capabilities of IEEE 802.1 TSN technologies. The system is built around ISO/OSI Layers 3 to
7, and adopts IEEE 802.1AS and IEEE 802.1Qbv standards concerning synchronisation and scheduled traffic. By choosing the CLPA and
its technologies, such as CC-Link IE TSN, end users can rely on network solutions at the forefront of automation. Industries can adapt to growing manufacturing demands and more easily turn their factories into smart, interconnected systems.
FUTURE IMPACT OF TSN Addressing the communications
DESIGN SOLUTIONS | SEPTEMBER 2019 33
develops CC-Link IE compatible devices, but also submits its CC-link IE products to conduct CLPA conformance testing. Network switches are particularly important to ensure connectivity for automation components, so it is highly advantageous for Phoenix Contact to ensure CLPA conformance for its CC-Link IE network switches. Of particular interest is the recently certified FL SWITCH 2000 family of managed switches. These are intelligent systems designed to maximise flexibility, robustness and stability of industrial automation networks. Aulenberg commented: “Firstly, we certified three FL SWITCH 2000 switches with up to eight ports according to CLPA specifications. Now, we are planning for our switches with up to 16 ports and fibre ports to undergo CLPA conformance testing soon.” When thinking about future developments, Phoenix Contact strongly believes that TSN will be one of them. “TSN is so important because – together with other big digital communications innovations, like 5G or 2-wire Ethernet – it will have a big impact on the automation systems of the future. With them, it will be possible to set up a system that will outperform today’s systems. “TSN is intended to bring real-time
capabilities into standard Ethernet. The main advantages of TSN are time synchronisation opportunities and the prioritisation of time- critical data traffic,” concluded Aulenberg.
CLPA
eu.cc-link.org
Phoenix Contact develops CC-Link IE compatible devices and, when thinking about future developments, strongly believes that TSN will be one of them
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