Alexander Bergner, TTTech Computertechnik: "Edge controllers can take over the logic functions of the PLC."

© TTTech Computer Technology

What role will edge controllers and which PLCs will play in the future? Or will the two concepts even merge?

Edge controllers will enable cloud concepts at machine level and integrate existing control concepts. Alexander Bergner, Product Manager Industrial IoT at TTTech Computertechnik, explains how this will work.

Markt&Technik: What are edge controllers actually about?
Alexander Bergner: Edge controllers are devices that enable the use of cloud technologies in production halls and machines. By using virtualization, they overcome the current restrictions of embedded systems and enable greater flexibility from the control level upwards.

What role will edge controllers play in Industry 4.0?
Alexander Bergner : Key issues for Industry 4.0 are data consistency and flexibility. These aspects are integrally supported by edge controllers. The devices will form the infrastructure on which programs from the various software levels of industrial production are executed.

What tasks could edge controllers take over from the PLC?
Alexander Bergner: Edge controllers can take over the logic functions of the PLC. I/O terminals are controlled via bus couplers, more complex sensors or actuators directly via Ethernet-based fieldbuses.

To what extent are edge controllers capable of hard real-time?
Alexander Bergner: With current virtualization technology, cycle times of 1 ms are easily achievable. It is therefore quite realistic that motion control tasks will be taken over by edge controllers in the future.

What significance do the IEC 61131 programming languages known from the PLC world have for edge computing, and which other programming languages?
Alexander Bergner: Edge controllers do not break with the familiar control concepts. The PLC is an application on an edge controller like any other - but with increased demands on the real-time capability of the system. In this respect, edge controllers can still be programmed using the familiar IEC 61131 languages. Of course, other concepts are also conceivable - from Matlab to C#. The flexibility of edge controllers will make it easier for users to choose between alternatives. The variety of programming languages used is therefore likely to increase.

Connect the controller to the sensors!

Rahman Jamal, National Instruments: "Edge controllers allow data to be quickly analyzed and filtered directly at the point of action, i.e. where the sensors are located."

© National Instruments

The more sensor data is recorded and processed in production, the closer the controller needs to be to the sensors. Edge computing is the right concept for this, emphasizes Rahman Jamal, Global Technology and Marketing Director at National Instruments, and explains the background.

Markt&Technik: How do you explain the trend towards edge computing?
Rahman Jamal: Over the past decade, the intelligence of data acquisition devices and sensors has grown considerably and become more decentralized. The processing elements have moved closer to the sensor. Nowadays, intelligent sensors combine the sensor, signal conditioning, embedded processing and digital interface in an extremely small system. In view of this development, the focus in many scenarios is now on intelligence and signal processing directly at the edge.

How do you define the term edge controller?
Rahman Jamal : As I understand it, controllers that are used at the "edge" of the Internet are referred to as "edge controllers" or synonymously as "fog controllers". The term 'fog computing' is intended to indicate that the controller is not located in the cloud, i.e. up in the cloud of the network, but in the "fog" down on the ground. As a local controller, an edge controller provides excellent services for the IIoT, as it takes care of data transmission to the decentralized data center and can thus relieve it. On the one hand, it allows data to be quickly analyzed and filtered directly at the point of action, i.e. where the sensors are located. On the other hand, it can also serve as a cache. A nice side effect of this is that it can counteract bottlenecks in internet bandwidth.sensors and actuators located directly at the "edge" of IoT systems are currently springing up like mushrooms. This is where large amounts of data from the physical world - what we call "big analog data" - are generated and converted into a digital signal. If the data is analyzed directly at the sensors and actuators, i.e. very early in their life cycle, valuable information can be extracted from it more quickly.

What does this mean for the measurement system software?
Rahman Jamal: Because processing is moving closer to the sensor, innovations in measurement system software must also ensure that analysis is moved further towards the edge. Future software for edge-based systems will make it possible to quickly configure and manage thousands of networked measurement devices and transfer a vast amount of analysis and signal processing data to these nodes. Companies will need to move to more intelligent software-based measurement nodes to keep up with the amount of analog data they will generate.

What are the implications for the enterprise level?
Once intelligent systems have captured the data, the next step is to make the data available to the company so that it can be efficiently managed, consolidated and analyzed. An enterprise-wide data management and analytics solution that can handle engineering data from multiple sources is essential to get the right data to the right people at the right time so they can make informed decisions based on the data.

What role will edge controllers play in Industry 4.0?
Rahman Jamal : The topic of IoT or Industry 4.0 has a major impact on manufacturing technology. It really is about the next big "thing": a network of thousands of sensors equipped with unprecedented embedded intelligence that collect vast amounts of big analog data, which is then forwarded via extremely fast wireless networks. However, because it is also ultimately important in production to have the right information at hand in good time in order to make the right decisions, it is no longer enough for controllers to simply take on control tasks. The requirements of the IIoT are constantly changing, meaning that controllers must be capable of much more and also provide enormous computing power, communication options and precise control at the same time.

What tasks could edge controllers take over from the PLC?
Rahman Jamal : We are already seeing a demand for systems with smart edge architecture in production. In addition, we are already seeing a change in control technology with classic PLCs: PLCs are less responsible for control and are developing more in the direction of smart edge measurement technology. Tasks such as image processing or data evaluation are performed directly at the edge. Industrial systems and machines are becoming increasingly complex and often comprise several independent subsystems for very specific tasks such as image processing, motor control and the human-machine interface. In future, such an environment will require controllers that take a centralized approach and perform many or even all of these tasks in addition to control and regulation functions.

The PLC becomes an edge controller

Dr. Bernhard Quendt, Siemens: "The PLC can be expanded into an edge controller relatively easily and retains its hard real-time capability without compromising."

© Siemens

On the way to Industry 4.0, the PLC remains true to itself on the one hand and develops into an edge controller on the other. Dr. Bernhard Quendt, CTO of the Siemens Digital Factory Division, resolves the apparent contradiction.

Markt&Technik: Is an edge controller fundamentally different from a PLC?
Dr. Bernhard Quendt : The PLC has been a kind of edge controller for decades, when the term didn't even exist. It forms the boundary to the physical world. In automation, the world beyond the physical world was previously rather small, but in recent years this is where the greatest growth in data volume has been seen. Accordingly, the PLC has adapted its external interfaces by being able to integrate better than before into IT worlds in which Ethernet and protocols based on it dominate.

How is the structure of automation systems changing on the way to Industry 4.0?
Dr. Bernhard Quendt: Industry 4.0 continues to drive change in terms of data volumes and their processing. In the previous automation pyramid, the width of a level roughly corresponded to the amount of data it generated. In this respect, the pyramid will be virtually turned on its head with further digitalization. The functionality of the previous levels will be retained, but the previously fixed assignment of levels to dedicated devices will disappear. As an edge controller and controller-level device, the PLC will also perform functions at SCADA or MES level as part of Industry 4.0, for example.

What features qualify today's PLCs for edge computing?
Dr. Bernhard Quendt : At the moment, opposing concepts are being propagated here that are actually not so opposing, but rather merge seamlessly into one another. The PLC is characterized by the fact that it monitors and controls a physical process which, depending on the application and industry, has high requirements in terms of determinism and response time. The PLC is also increasingly able to take on tasks that require non-time-critical data pre-processing as close as possible to the process. By using multi-core processors in the PLC, it has sufficient free computing power and can also ensure that the additional data processing has no negative impact on the quality of real-time critical process control. The PLC is thus extended to become an edge controller.

Can edge controllers even achieve hard real-time?
Dr. Bernhard Quendt: That depends on the manufacturer. Today's edge controllers are often unable to achieve this because they usually come from companies that have previously dealt with pure data processing, where there was no correlation with the physical world and hard real-time was rarely a requirement.
As already mentioned, the PLC can be upgraded to an edge controller relatively easily and retains its hard real-time capability without any compromises. If, on the other hand, a previous edge controller is to gradually become real-time capable, the industry knowledge must be adapted in addition to the pure technology, because the PLC is now the standard for factory or process automation.

Which programming languages can be used to program PLCs that have been developed into edge controllers?
Dr. Bernhard Quendt: The future edge controllers based on the PLC will combine the best of two worlds. The real-time part will continue to use IEC 61131 languages, while the integrated edge controller will understand the languages commonly used there. The most important thing here is a consistent data world, so that the same symbols on both sides also refer to the same data. However, the data sovereignty here clearly lies with the PLC, because controlling the physical process is still more important than parallel or downstream processing of certain process values for optimization or traceability.

Server on the machine

Christoph Müller, Beck IPC: "An edge device behaves like a server and not like a PC or a controller with a proprietary OS."

© Market&Technology

Edge controllers behave like servers on machines; they control, communicate in all directions and ensure data security. But what do they do with the PLC? Christoph Müller, Business Development Manager at Beck IPC, outlines the future distribution of tasks.

Markt&Technik: How do you define the term edge controller?
Christoph Müller: It's funny that this term is so popular and yet not properly defined. Hardly anyone knows what it means. Most systems that I have come across as edge devices are nothing more than a PLC or an intelligent gateway that also communicates with a cloud (intranet/internet). Such a device should actually include additional cybersecurity functions, although for me this is self-evident. Who would connect a PLC to the Internet without appropriate protection!

The most important distinction from my point of view, however, is that an edge device behaves like a server and not like a PC or a controller with a proprietary OS. It should be possible to install the technologies that I use on the Internet, such as databases, brokers and firewalls, as well as modern programming environments such as Node Red.

What tasks will edge controllers take on in Industry 4.0?
Christoph Müller: They are cognitive and cooperative assistants to the production cells, in which the PLC will purely take care of control tasks. Topics such as recipes, alarm handling and reporting simply no longer belong in a controller or an HMI - these are IT topics. Another important point in the intranet is IT security. Edge nodes are much better suited to solving these tasks in the future.

According to the German government's definition, Industry 4.0 usually takes place in a closed communication environment. Here, edge nodes will communicate simultaneously with hundreds of production units such as robots and handling systems and ensure that they interact cooperatively with each other, telling everyone what they need to know and finding out from everyone what is important. Production data, but also machine data that minimizes downtimes or set-up times, is already being processed at IT level on the store floor, because an edge node can provide completely different apps than a PLC.

And what happens when communication goes beyond the intranet?
Christoph Müller: The whole thing changes dramatically, of course, when these systems leave the intranet and communicate with other systems on the internet. Then I need a controller that can communicate in real time with its sensors and actuators as well as subordinate control systems, but also communicates in "real time" and bidirectionally on the internet, tweets, sends WhatsApp messages and provides data to an AI. However, hardly anyone does this today.

TSN will play a decisive role at field level. Only time will tell whether OPC UA will also become established outside the intranet. I am rather sceptical about this because Internet technologies are difficult to standardize. Function goes before standard. In the future, the tasks ahead of us will increasingly be tackled by disruptive technologies, which in turn will be replaced after a few years. However, it is impossible to standardize them because they do not yet exist. Companies like Apple or Uber would certainly not have allowed themselves to be held back by standards.

Could edge controllers replace PLCs completely at some point?
Christoph Müller: Yes, of course they will replace the PLC completely one day, but will it then be an edge controller or just a PLC with extended communication, cyber security and server functions? Such a "thing" controls, communicates locally and communicates with the cloud. However, it will definitely take over tasks such as recipe management, alarming or reporting that are currently performed either in the PLC or in an HMI. The topic of HMI will also change massively thanks to edge controllers, because I will then be able to run convenient web-based visualizations there and only need a low-cost, high-performance browser panel or a mobile smart device as an end device.

To what extent are edge controllers capable of hard real-time?
Christoph Müller: As soon as TSN has gained a foothold.

Which programming languages can be used to program edge controllers?
Christoph Müller: With Node Red or Javascript, for example. But the question is much more about who will write applications from where in the future. Crowd sourcing and AI will change a lot here.

What role will the IEC 61131 programming languages familiar from the PLC world play in edge computing?
Christoph Müller: Hopefully no more. These programming languages are more than 20 years old. I don't think that young people who are dedicated to the topic of modern manufacturing really want to program with structured text anymore.