Editor's Choice


20 years of EtherCAT

October 2023 Editor's Choice

EtherCAT Technology Group (ETG) will be holding a series of exclusive breakfast seminars across the country at the end of October and will be celebrating ‘20 years of EtherCAT’. Further details are at www.ethercat.org/2023/southafrica. Here is executive director, Martin Rostan’s Q&A account of EtherCAT’s remarkable history.

20 years of EtherCAT: how did it actually start back then?

Beckhoff had already launched the Lightbus in 1989, an optical fibre-based bus system for fast communication with input and output modules. The Lightbus had a transmission rate of 2,5 Mbit/s and already used the principle of processing on the fly. At the end of the nineties the next generation of this fibre optic technology, with a higher transmission rate, was developed. The project name was Fast Lightbus. At 50 Mbit/s, this would have been significantly faster, but somehow we felt that something was still missing. This came with the idea of linking the Lightbus principle with Ethernet. At that time, the use of Ethernet at the field level was just emerging, and this also fitted in well with the Beckhoff approach of using technologies from the IT world for automation technology, thus benefitting from the much larger IT market. After all, Beckhoff was the pioneer of PC-based control technology, which follows the same approach.


Martin Rostan, executive director of the EtherCAT Technology Group.

What is special about the principle of processing on the fly?

Instead of sending a telegram to each network node in each cycle, and receiving a telegram from each node, a single, correspondingly longer telegram is sent through all nodes and processed by them on the fly, almost without delay. Each node reads the output process data intended for it and inserts its input data into the same telegram. Since the network nodes have been informed beforehand where the respective process data is to be found in the frame, no node-related address information has to be carried along. Thus a bit remains a bit and does not become a whole frame. This is how we achieve maximum efficiency. Typically, over 90% of the entire telegram is used for process data. So the bandwidth is used the most efficiently; and since the same frame is used for input and output data, the available bandwidth can usually even be doubled. This is why EtherCAT achieves such high performance.

EtherCAT is often referred to as the fastest fieldbus solution. Why is that so important?

For every control engineer, it is obvious that shorter cycle times mean better control quality, and ultimately leads to better product quality. This applies not only to all applications with a motion control component, but also to measurement tasks. Thanks to PC-based controllers, computing power is no longer a bottleneck − the bus system is usually the limiting factor. For this reason, the performance of the bus system has also become increasingly important. Anyone who combines a control system that can handle cycle times in the sub-millisecond range with a bus system that cannot keep up, is doing something wrong.

It is less obvious how applications with so-called transitions benefit from the shorter cycle time, thanks to EtherCAT, and thus from faster response times. The controller may wait only a few milliseconds at a time for a sensor signal confirming the arrival of the part or the reaching of the target position before moving on to the next process step; but reducing these small waiting times is worthwhile, and leads to measurably better efficiency and more machine throughput.

That’s some sophisticated technical reasoning, do users go along with it?

That’s right. With EtherCAT, we go much deeper into the technical arguments than are usual with most fieldbus organisations. That is exactly our approach − convince with convincing technology. This is what gives engineers particular pleasure. When we presented EtherCAT for the first time at the Hanover Fair in April 2003, we were not able to score points as a large user organisation, nor was Beckhoff yet one of the large suppliers of automation solutions whose technology practically spread on its own due to its market significance. So we explained the special features of our new technology and initially won over those users who were quickest to recognise the benefits of the exceptional performance of EtherCAT.

Then you founded the EtherCAT Technology Group with them?

Correct. Of the 33 founding members of the ETG, half were users, not manufacturers of automation systems, and they were usually considered to be technology leaders in their industry. In other words, they were companies that were used to convincing with convincing technology. Of course, it also helped to overcome the chicken-and-egg problem to start with users right away.

The chicken-and-egg problem?

Yes, that’s one of the challenges when introducing a new technology. The vendors only implement the technology when users ask for it; and users can only be won over when there are suppliers for the corresponding devices. Another challenge was that we did not have any cost-effective EtherCAT chips at the beginning, but had to work with FPGAs, which were still very expensive back then. An EtherCAT interface still cost a lot of money at that time. With the availability of the first EtherCAT ASICs in 2006 the problem was solved quickly. In the meantime, the chips are available from 13 different manufacturers and the interface costs are lower than those of classic fieldbus systems, not to mention other Industrial Ethernet solutions. With EtherCAT, a standard Ethernet port in the controller is sufficient, which has helped us a lot in spreading the technology.

Speaking of popularity, on the occasion of 20 years of EtherCAT, the ETG has published figures for the first time, and they differ significantly from the known market studies. Why?

This is because it’s the first time. We were previously reluctant to do so for two reasons. Initially, FPGA-based devices dominated, and we did not know their quantities. We could not yet count and leave out the modular devices, the EtherCAT terminals. After all, it would be misleading to count a modular I/O station with 50 electronic terminals as 50 EtherCAT nodes, even if these are actually 50 EtherCAT nodes. In the meantime, however, these bus terminals use special chips, and we assume the share of FPGA-based devices to be less than 10%, so that the fuzziness in their number does not matter. So we arrive at almost 60 million EtherCAT devices, without counting the bus terminals. That should mean market leadership.

With over 7200 member companies, the ETG is also the world’s largest fieldbus association. How has this come about?

While the technology and its user benefits are certainly in the foreground, the extraordinarily dedicated team of the EtherCAT Technology Group has contributed decisively to the success of EtherCAT. The tech team not only coordinates the technical working groups, writes specifications and represents EtherCAT in the various standardisation bodies, but above all supports our members in implementing the technology. This means tech support and workshops, and also regular interoperability meetings, so-called plugfests, which we hold worldwide. Our members highly appreciate the quality of our implementation support, and actively contribute to it through the very comprehensive developer forum in the members area of our website.

The marketing team is equally committed to organising high-quality trade show booths and technology seminars, which we have now held in over 50 countries.

At the beginning, I would not have thought that 1000 member companies would be possible, and so far the growth is still not slowing down. Meanwhile, almost 500 new member companies are added every year, which also shows how busy the membership administration is.

Is this all organised from Germany?

Although the headquarters of the EtherCAT Technology Group is in Germany, we have offices in China, Korea, Japan and the USA, which operate pretty independently and support the members locally. Over 3000 member companies from Asia show that EtherCAT is also a leader on this continent. With over 1000 members in the Americas, the ETG is the fieldbus association with the largest membership there as well. We are looking forward to the worldwide team finally coming together again soon to celebrate 20 years of the EtherCAT Technology Group in a proper way. But before that we will celebrate with the members. At the next meetings of the Technical and Marketing Committee there will be festive evenings. There is a lot to celebrate, and certainly special EtherCAT applications are part of it.

Yes, of course some EtherCAT applications are particularly rewarding. For me, as a sailor, the high-tech yachts in the America’s Cup are among them, all of which use EtherCAT. I hope to make it to the regattas in Barcelona next year. And since I am an aerospace engineer, EtherCAT in space excites me. EtherCAT has already been used on the ISS and was selected for the robot arms on the Lunar Gateway space station. But EtherCAT also rides on tractors, and helps with the experiments that have won Nobel Prizes in physics.

All this only because EtherCAT is so fast?

No. The performance of EtherCAT is often highlighted, but our special functional principle has many more advantages. For example, we can automatically address the network nodes during startup, which greatly simplifies commissioning. We can synchronise the nodes with high precision, even without special hardware in the controller. EtherCAT users do not need any IT know-how or switches, and therefore do not have to buy, install and configure them, nor are they limited by cascaded switches. We can therefore create line topologies with almost any number of nodes − but not only the line, also branches, tree topologies and rings for line redundancy, and that without special redundancy nodes. We have built special diagnostic features into the EtherCAT chips that help us to not only reliably detect bit errors and even loose connectors, but even to localise them. All this saves a lot of time and money. So EtherCAT has a whole bundle of unique selling points, which makes it very easy for us to promote it.

The other bus technologies are on your heels and are challenging your unique selling points with new versions. Gigabit and TSN are starting to arrive in the fieldbus market.

Yes, the competition is trying very hard, and keeps inventing new versions to close the gap between us. With Gigabit and TSN technologies they try to catch up with our performance advantage. But anyone who can do the maths quickly realises that the EtherCAT functional principle cannot be beaten, even with Gigabit. EtherCAT will continue to perform better even at 100 Mbit/s, when realistic scenarios are compared. For applications that actually require more bandwidth, we have EtherCAT G in preparation.

The beauty of our extension to higher bit rates is that it will not be a new version of EtherCAT, but an extension. The more robust 100 Mbit/s technology will not be replaced by EtherCAT G, but supplemented where the application requires more bandwidth. I assume that even in 15 years, 95% of the EtherCAT devices will use 100 Mbit/s. This maintains the stability of EtherCAT. We have always only enhanced EtherCAT, never changed it. This means that you can use a current EtherCAT device in a system from 2004 without any problems, while our competition keeps releasing new, even more complicated versions that are not downward compatible.

How do you see the next 20 years for EtherCAT?

Twenty years ago I boldly predicted that ten years later EtherCAT would be number two in the market. Another ten years later we are even further ahead. I don’t see any development that should change that. With EtherCAT G, we are enhancing our technology for application areas that require even more bandwidth, and we are making EtherCAT future-proof. When I look at the membership growth of the EtherCAT Technology Group, the end of the line is obviously far from being reached.

For more information contact Martin Rostan, EtherCAT Technology Group, +49 911 540 5611, m.rostan@ethercat.org, www.ethercat.rocks




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