COVER STORY ADVERTISEMENT FEATURE
For these standards, special hardware support and, thus, special ASICs are needed. Because PROFINET RT and EtherNet/IP are also based on the embedded two-port switch with cut- through, they are also not exempt here. Flexible hardware-based multiprotocol solutions such as Analog Devices’ fido5000 solve the problem in an elegant manner.
ENTER TSN With TSN, extensions for standard Ethernet in accordance with IEEE 802.1 that break free of past limitations have successfully been developed. Thus, there is now a standardised layer 2 in the ISO 7-layer model with upward compatibility to the previous Ethernet and hard real- time capability. With 802.1AS-rev, TSN also defines an interoperable, uniform method for synchronizing distributed clocks in the network. Because best effort communication always takes place with TSN, the common use of a cable is possible for hard real-time applications, as well as all other applications (web server, SSH, etc.). TSN is not dissimilar to PROFINET IRT in that regard, and it also offers comparable performance. What’s new with TSN is the need for
more extensive network configuration. Centralised or decentralised configuration is possible. Both types of configuration are currently being discussed and implemented. Interoperability between the two configuration mechanisms is a future development goal.
WHAT ARE THE PRACTICAL ADVANTAGES OF TSN? The most common answer is that with a larger market, less expensive network interfaces also appear on the market. After all, TSN will also be found in building automation and the automotive industry in the future. As a matter of fact, the market for embedded TSN solutions is expected to be significantly bigger than the current market for all industrial Ethernet solutions put together. The greatest technical advantage of
TSN over previous industrial Ethernet methods is its scalability. Unlike current industrial networks, TSN was not defined for a specific transmission rate. TSN can be used for 100Mbps just as for 1Gbps, 10Mbps, or 5Gbps. It also enables topologies to be better optimised because now adapted data
PROFINET and EtherNet/IP plan to make their complete protocols available right on TSN as layer 2. This makes stepwise transition to TSN possible. In summary, TSN will be found
everywhere in new installations as well as in the form of islands or segments introduced incrementally into existing installations. However, with TSN, there will be new
Figure 4. Brownfield: TSN segment combined with PROFINET and EtherCAT
rates can be selected for various segments. Whether it’s Gbps, 100 Mbps, or 10Mbps, a unified layer 2, IEEE802.1/TSN, is used. A uniform network infrastructure also
helps personnel tasked with setting up and maintaining the network because, thanks to TSN, solutions can now be used in sectors other than automation: building, process, and factory automation and energy distribution alike. This brings us to the next advantage, the training factor. TSN is already a topic at many universities, mostly in the research stage. However, technical and vocational colleges are already showing interest in this topic. We can fairly safely say that TSN will become basic knowledge for engineers, technicians, and skilled workers. Retraining for different fieldbuses will no longer be necessary.
BROWNFIELD, OR WHAT WILL HAPPEN TO TODAY’S PROTOCOLS? In nearly all TSN-related working groups there is a recurring theme: how to safeguard the transition to TSN and the supply to existing installations, such as Brownfield applications? On all sides, emphasis is being placed
Figure 3. Timing model: PHYs, cables, and switches contribute to delays in data transmission. This must be considered with the time slot method (PROFINET IRT and TSN time aware shaper (TAS))
on making it possible for customers to transition to TSN easily and smoothly. It can already be said today that the existing industrial Ethernet protocols are not just going to vanish overnight. On the contrary, anyone using PROFINET, EtherNet/IP, EtherCAT, or a similarly widespread industrial Ethernet protocol today can safely assume that he or she will also be able to operate networks with these protocols, and receive support and replacement parts, in 10 years’ time. All industrial Ethernet organisations
provide models that describe how existing plants can cooperate with new TSN-based devices. The interface to the existing industrial network is made by a gateway (Sercos), with a coupler (EtherCAT), or without any special hardware (PROFINET RT). Especially
/AUTOMATION
players in the industrial Ethernet field. OPC UA, which, with the new transport protocol PUB/SUB, in conjunction with TSN, is already viewed as a competitor to the classic protocols. For the manufacturers of field devices, this means that the classic industrial Ethernet solutions as well as TSN and the new players will have to be supported.
TSN AND ANALOG DEVICES Analog Devices acquired Innovasic, an industrial Ethernet leader, a little over one year ago and has now successfully integrated it. Along with Innovasic, the fido5000 series of industrial two-port switches was incorporated into the Analog Devices portfolio. The switches in the fido5000 series support all relevant industrial Ethernet protocols and are already TSN ready. With the fido5000, products that enable the transition to TSN and simultaneously meet today’s requirements (PROFINET IRT, EtherCAT, POWERLINK, EtherNet/IP, etc.) can already be planned today. OPC UA PUB/SUB will also be possible with the fido5000. Thanks to the fido5000, TSN will become an update that can be planned for existing systems. The fido5000 series is undergoing
continuous enhancement for this. New products for Gb applications will be offered, but the 10 Mb/100 Mb products will also be continued and adapted to customer requirements. Migration to TSN will be able to be
performed reliably and efficiently thanks to the flexibility afforded by the fido5000 series.
TSN AS AN OPPORTUNITY TSN makes it possible to create a uniform basis for all industrial communications. Once TSN is introduced, layers 1, 2, and 3 of the ISO 7-layer model will be unified in industry. This will make completely new levels of scalability and performance possible. Will communication on the upper layers also be standardised based on this? Will there be a unified OPC UA PUB/SUB? Possibly. With the fido5000 series, users are prepared for all scenarios.
Analog Devices
www.analog.com
T: 01628 477066
AUTOMATION | MAY 2018 9
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