Standards and Industry 4.0: PROFIBUS and PROFINET

Standards and Industry 4.0:

PROFIBUS and PROFINET

Interview with Michael Bowne, Executive Director, PI North America, PROFIBUS and PROFINET

Standards are important to the latest industrial revolution. Profibus, for example, is a digital network based on serial communication, and standardized in IEC61158 and IEC 61784, which can be used for both high-speed time-critical applications and complex communication tasks. Michael Bowne tells us more.

Michael Bowne, Executive Director, PI North America, PROFIBUS and PROFINET

Video:

Industry 4.0 TV Talks To Profibus Profinet At The Advanced Engineering Show, Birmingham

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Standards and Industry 4.0

Issue no 9 - February 2019 industry 4.0

Please could you say something about Profibus in the context of Industry 4.0?

“The fieldbus wars from the 1990’s are over. Profibus has become the de-facto fieldbus standard for automated manufacturing. Performance was a key driver of mass adoption, achieved by creating a closed network.

But this came at the expense of flexibility. Industrial Ethernet was a step in the right direction with its openness. Now, it’s all about the data.”

What challenges are presented by Industry 4.0 and standards?

“It’s always been about the data. If we think back to what made fieldbuses so revolutionary— the move from analog to digital—it was nothing short of a step-change. And while replacing 25 wires with just one wire was great, the real cost savings came from less tangible features. Increased data capacity, high-speed networks, diagnostics: these were the features that made it possible for us to sell 60 million Profibus nodes. They led to benefits like decreased downtime, increased transparency, shorter throughputs and overall greater efficiency.

“The move from fieldbuses to Ethernet-based networks was another step-change. Serial fieldbuses achieved their determinism by virtue of the fact that they were a closed network. Likewise, a control network that leverages standard unmodified Ethernet to allow deterministic data exchange to coexist with other protocols—all on the same physical layer—is monumental. This is what made it possible for us to sell 25 million Profinet nodes.

“The foundational reasons for employing industrial Ethernet to enable Industry 4.0 are well known— they create enterprise-wide transparency, ease data access, and provide standardized interfaces with broadly familiar mechanisms.

“And while it may be popular to dismiss phrases like “enabling Industry 4.0,” which I used above, it’s important to understand that this is not just some flippant turn-of-phrase. Sure, it may have once seemed that such phrases were just different words for what we’ve been trying to do all along. But it’s becoming increasingly clear that something more is happening—and it appears that a convergence of information technology (IT) networks and operational technology (OT) networks is the key.

“But what does it all really mean? From a classic ISA95 perspective, it means that the field level and the MES (manufacturing execution system) level are getting closer.

“In the traditional ISA95 model, industrial Ethernet only plays a role at the lowest level (OT) in the field. From there, it connects to the controls level, which then interfaces to an MES (IT) with the primary goal being to run the plant. With Industry 4.0 and the Industrial Internet of Things entering the scene, however, the boundaries between these levels are blurring. As a result, the relationship between the field level and the MES level is set to expand.”

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industry 4.0 Issue no 9 - February 2019 Standards and Industry 4.0

What is being done in the way of adaption? “So how can we take a step forward in terms of diagnostics in the context of Industry 4.0? The answer is OPC UA. Currently within Profibus/Profinet International (PI) we are working diligently on a companion specification between Profinet and OPC UA. One of the first areas of our focus is on diagnostics. By mapping Profinet diagnostic data to OPC UA, this information can more easily be consumed by IT software packages like MES. Such standardized information flow should ultimately help minimize unplanned downtime.

“As far as performance is concerned, the path is clear: run production at the rate that maximizes throughput. For Profinet, network speed and determinism have always been priorities.

Like anything, throughput itself is a complex equation, and network performance is just one part. But maintaining an open network infrastructure while simultaneously providing high performance is nothing new.

“So how can we take a step further in terms of network performance in the context of converged IT/OT networks? The answer is Time Sensitive Networking (TSN). The techniques that have allowed Profinet networks to be both high performing and open since the early 2000s are now becoming IEEE Ethernet standards. Eventually TSN will become the first layer in the foundation of a converged IT/OT network. And since Profinet is based on standard unmodified Ethernet, as TSN becomes integrated into Ethernet itself, those features will be inherent.”

What of the future?“2019 is shaping up to be a very big year—at least it is for PI. With a number of major releases planned, now is the time to become familiar with three major technological advancements.

“But first, these past couple of years have been busy ones for the Working Groups of PI. Working Groups develop all the technical advancements made to the Profibus, Profinet and IO-Link specifications. These groups are staffed by some of the smartest engineers in the industry from companies big and small. These folks volunteer their time to help drive our technologies forward—and one Working Group has been particularly busy.

“The Industrie 4.0 Working Group (I4.0 WG) was initially convened in 2015 when trends like the Industrial Internet of Things were first gaining traction. At the time, the group was tasked “with turning concepts into reality. Instead of blindly adopting new technologies for technology’s sake, a different approach was taken. Collaborating with end-users across vertical markets, the group first developed a long list of requirements. These requirements were then prioritized, which resulted in three main areas being highlighted—simplification, integration and process.

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Simplification“TSN is all about making life less complicated when it comes to deterministic networking—a fundamental aspect of factory automation— over Ethernet. With Profibus, determinism was achieved via a closed fieldbus. However, since Profinet runs on standard open Ethernet, which is not deterministic by design, additional functions were built into the Profinet protocol to achieve this determinism. Namely, the protocol skips Layers 3-4 of the ISO/OSI Model and goes straight from Layer 2 to Layer 7. Furthermore, Profinet Isochronous Real Time (IRT) adds features like bandwidth reservation, synchronization and scheduling to function even faster for high-speed motion control.

“Now that other industries outside of factory automation are interested in deterministic Ethernet, the features we’ve built into Profinet for 15 years are becoming IEEE standards known as TSN. This simplifies networking, as determinism can be taken for granted via TSN mechanisms. While it may sound trivial to bring the TSN tools into the Profinet specification, it has taken a few years of continuous effort within the I4.0 WG to make this happen. In mid-2019, PI will release its Profinet@TSN spec, and we expect the first products with this technology to hit the market in 2020.

Standards and Industry 4.0Issue no 9 - February 2019 industry 4.0

Integration

“Another topic highlighted in the Working Group is horizontal/vertical integration—which focuses on reducing the effort to gain access to manufacturing line data and harmonize it for additional use. To that end, PI plans to release its Profinet/OPC UA Companion Specification by mid-2019.

“Of course, machine-to-machine (horizontal) integration is nothing new for Profinet. In fact, the very first version of the protocol was used in this fashion before being expanded to I/O data exchange. With this history in mind—plus the knowledge of OPC UA’s capabilities and widespread acceptance—the I4.0 Working Group determined OPC UA to be the best way to integrate Profinet from controller to controller. In combination with TSN, OPC UA allows best-in-class machines from various vendors to communicate deterministically.

“For vertical integration applications, the Profinet/OPC UA Companion Specification will begin with a mapping of Profinet diagnostics and asset management records to OPC UA objects. With such data made available via OPC UA, it can be accessed more easily by higher level systems. For example, with diagnostics mapping, the Alarms & Conditions functionality of OPC UA could be leveraged by Profinet. For Asset Management Records, the goal is to further advance the concept of the Administration Shell within the context of digitalization.

The ability to gather detailed Asset Management Records from Profinet devices via OPC UA will help in the creation of a digital twin for any given machine.

“Whenever the topic of vertical integration is discussed, the first question always raised is about security, and this issue is being addressed by PI’s I4.0 Working Group. The challenge with industrial control system security is to strike a balance between going too far and not going far enough. With this in mind, since the first security implementations were demonstrated in April 2018, the Working Group’s initial focus has been on mitigating potential man-in-the-middle attacks.

“Given that most Profinet traffic is transmitted at Layer 2 of the ISO/OSI Model, its packets are distributed according to MAC address. By definition, packets at this level do not traverse different subnets and are not routable according to IP addresses. Therefore, a malicious actor would need to be inside a target network to do something nefarious with these packets. Of course, if a hacker is already inside the network, there are bigger problems to worry about. However, because Profinet uses IP addresses in certain instances to route traffic that is not time critical, these instances could be more susceptible to manin-the-middle attacks. That’s why the Working Group’s efforts to secure the protocol are being focused here first.

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industry 4.0 Issue no 9 - February 2019 Standards and Industry 4.0

Video:

OPC UA in PROFINET networks

Process

“If the TSN advancements will be felt most in discrete manufacturing, then the advancements to Ethernet known as Advanced Physical Layer (APL) will be felt most in continuous process control applications. The reasons for the difference here are that TSN mechanisms operate at Layer 2 of the ISO/OSI Model, whereas APL operates at Layer 1. The ultimate goal for the process industries is to bring Ethernet down to field level instruments in hazardous areas.

“As instruments get more complex and more data becomes available, the need for increased bandwidth to access this data becomes apparent. Ethernet provides this, with the added benefit of being a well-known standard.

The forthcoming APL will be based on single pair cabling, already familiar from the Profibus PA world. Similarly, both power and communication will be transmitted via these wires. Finally, APL will exceed the 100m limit currently imposed on common 100Base-TX Ethernet networks.

“Since this is an advance of Ethernet itself, and not just Profinet, PI is collaborating with other fieldbus organizations on this work. Therefore, the timeline for APL is a bit longer than that of the TSN implementation or the OPC UA Companion Specification. Work on APL is not expected to be completed before 2020 or 2021.

“We all know that in manufacturing markets things don’t happen quickly, but in reality, these technologies will be here before we know it.”

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