“For the user, standardised means future proof”

April 11, 2018 6:01 pm

Why is it significant that POWERLINK has been standardised as IEEE 61158?
It’s a differentiating factor that will further accelerate the spread and acceptance of POWERLINK. It makes implementation easier and cheaper. At the same time, it reminds us that Industrial Ethernet continues to gain significance. In the age of Industrial IoT and Industry 4.0, real-time communication is becoming more and more important.

What sets Industrial Ethernet apart from regular Ethernet?
Two things: determinism and semantic context. Working at our office PC, connected to a fast IT network, we may get the impression that we’re sending and receiving data more or less in real time – but that’s not the case. Whenever you have large numbers of simultaneous requests or large files being sent, the network may get sluggish or even crash. That can be frustrating, but it’s not the end of the world. In an industrial setting, network congestion can cause much bigger problems.

Like what?
Imagine an automotive assembly line with a robot that mounts the windshield onto the chassis. There are sensors that tell the robot how much farther to move until the windshield is in the right position. If the signal telling the robot to stop is delayed by just a second, or if the robot doesn’t understand the semantics of the message, you’re cleaning up a broken windshield. If a human operator is nearby, the consequences can be even more serious. That’s why it is imperative that all the data needed to control a machine is guaranteed to arrive at a clearly defined time and that it is understood by every node in the network.

How do you do that?
There are a number of mechanisms involved. The network nodes all need to be on the same page with regard to timing and data types, for example. This and many other functions are what’s provided by the Industrial Ethernet protocols.

Which brings us back to POWERLINK. How did it come to pass that POWERLINK is standardised by the IEEE?
For a long time, real-time communication was uncharted territory for the IEEE. That’s why, in 2014, I started pushing for the IES to address the topic. IES stands for Industrial Electronics Society – it’s a subgroup within the IEEE, the world’s largest professional organisation for electrical and electronics engineers. The IES sponsored a working group within the IEEE tasked with adopting a standard for real-time communication.

How does a working group like that operate?
We had 38 participants from all over the world – representing everything from industrial companies and consulting firms to universities and research institutes. We introduced a draft for the specification, and it was discussed exhaustively. But, the IEEE sets very strict criteria for new standards. Not only the technical content, but also potential conflicts with other IEEE standards, structure, formatting, even spelling and punctuation – were all checked, rechecked and fine tuned.

Were any protocols other than POWERLINK evaluated?
No. The working group was very quickly in agreement that POWERLINK satisfied the requirements of the IEEE perfectly. Not just because of its excellent technical qualities, but also the fact that it is 100% compatible with the Ethernet standard. As open source technology, POWERLINK also doesn’t have any proprietary rights to deal with.

When did the working group complete its evaluation?
There were several steps involved. First, we had a number of rounds of discussion and voting within the group. Next, a group was formed within the IEEE to conduct two rounds of voting on technical matters. Then the development process itself and the formal requirements were examined. This is a clearly defined process within the IEEE, and occurred over the first half of 2017. The final specification was published in August, and since then, POWERLINK is now officially IEEE 61158.

What advantages does this standardisation have for OEMs?
IEEE standards are valid for a minimum of ten years. So, for the user, standardised means future proof. It also guarantees interoperability of all POWERLINK devices, as long as manufacturers adhere to the standard. This same interoperability also applies to POWERLINK and OPC UA, by the way. The Ethernet POWERLINK Standardisation Group published the companion specification in early 2017.

Are there any other advantages?
I believe we’ll see manufacturers of microcontrollers for Ethernet hardware starting to implement POWERLINK more and more. Factory automation suppliers will benefit from more and cheaper Ethernet controllers with POWERLINK. Ultimately, plant and machinery operators who use POWERLINK will see their costs go down as well.

POWERLINK has been adopted by the IEEE under international standard IEEE 61158. It is the only Industrial Ethernet protocol to achieve this status. We asked Dietmar Bruckner, technical manager of open automation at B&R, to describe the standardisation process and explain what advantages we can expect to come out of it.
Dietmar Bruckner, Technical Manager of open automation, B&R