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WORLD OF INDUSTRIES 05/2018

WORLD OF INDUSTRIES 05/2018

New control platform

New control platform opens the way up to the next level of automation AUTOMATION PLCnext Technology forms the basis of the new, open control platform from Phoenix Contact and has been available to users as a released product since November 2017. Interested parties have had the opportunity as part of an Early Adopter Program to accompany the development of the platform from an early stage. The first ideas and applications developed from this activity, which are particularly sustainable. In order to understand the possibilities offered by the new control platform, its features should be briefly explained in comparison with established solutions. The classic PLC architecture is based on a runtime system implemented on a more or less familiar operating system. The runtime system is then programmed with a manufacturer-specific engineering tool. The system assumes execution and scheduling as well as consistent exchange of data between the tasks and programs defined in the runtime environment. Since the needs of users have changed considerably in recent years, and the demand for the controller to be programmable in high-level languages is continually increasing, PLC manufacturers are satisfying this demand with two different strategies. Programmable in high-level languages The first approach is characterized by various controller providers enabling engineering with the Microsoft Visual Studio, Eclipse and Matlab Simulink tools. The resulting programs are then compiled against the runtime available on the PLC and executed within the runtime. The advantage of this is that the programs can be created as usual by the controller programmer as a function block. One disadvantage of such a system in which the high-level language programs are encapsulated by a runtime environment of the operating system becomes evident if the user wants to use existing open source components. These, after all, are often dependent on functions of the operating system. If these are not provided by the PLC manufacturer in the runtime environment, the user is then subject to the same dependency that exists with classic control systems. Thus, the user cannot simply integrate a Java Runtime or a Python interpreter into his engineering activities when needed. Retaining specific advantages of previous approaches Another concept with which control providers are responding to the new demands of their customers is the provision of a Linux PC in an IP20 DIN rail housing. Here, the user has flexibility in decisions regarding the execution, programming and use of existing open-source libraries. However, such platforms are only of limited appeal to the classic PLC programmers because they cannot implement the engineering activities there in the familiar IEC61131 programming languages. Against this background, Phoenix Contact has combined the advantages of both approaches in PLCnext Technology and elimi- Author: Dipl.-Ing. Michael Gulsch, Marketing PLC, Phoenix Contact Electronics GmbH, Bad Pyrmont, Germany 14 WORLD OF INDUSTRIES 5/2018

nated the associated disadvantages. Based on a real-time Linux operating system, all PLCnext controllers incorporate an IEC61131 runtime environment. The classic PLC programmer can thus unpack the device, connect and program as usual, without having to learn the intricacies of Linux. At the same time, he receives a platform with the flexibility necessary for satisfying future requirements. PLCnext Technology is appealing to the high-level language programmer because he can create his application in all familiar engineering environments. Plug-ins are available for tools such as Microsoft Visual Studio, Eclipse, and Matlab Simulink that configure the compiler (ARM architecture, x86 architecture) and install various export filters. Bringing programs into a temporal context The PLCnext Technology is characterized by the scheduling being completely separated from the runtime environment and organized as a Linux component. In this way, any programs can be structured into tasks and put into a temporal context. This is one of the main differences to other control solutions available on the market which provide separate runtime systems for the execution of an IEC61131 task as well as for the high-level language part in one device. With this approach, the user can program in high-level languages as well as in IEC 61131, but his flexibility is limited because again he is dependent on the runtime environment of the respective manufacturer. In contrast, the architecture of the PLCnext Technology enables programs from any tool to be brought into a temporal context. For example, the user can execute the cycle time and execution sequence of an IEC61131, C ++, and Matlab Simulink program in one task. Or he can dispense with using the scheduler if he wants to implement programs that do not have to be processed in real time. This includes, for example, non-real-time protocols such as MQTT and Modbus/TCP as well as the processing of database clients such as Redis and SQL. Easy exchange of data between tasks and programs As a further simplification, the Global Data Space (GDS) enables the programmer to exchange process data between the tasks (threads) and programs via ports defined in the GDS. He is thus saved the hassle of using semaphores, resource blocking, and other programming techniques to consistently transfer data from one “PLCnext Technology departs from the patterns of thinking of programmers, users and manufacturers established over decades.” process to the next. Furthermore, the Global Data Space includes an interface that enables applications running outside of the realtime environment to write data to the GDS and read data there. This enables a simple link to be created between the real-time and non-real-time environments. The configuration of all components is based on XML files. Thus, as he is used to in Linux, the programmer can create and modify the scheduling and the process data assignment by editing a text file. Even greater convenience is provided by the PC Worx Engineer configuration and programming tool, which includes a graphical interface for setting up the Execution and Synchronization Manager (ESM) and the Global Data Space. In this way, programs can be assigned to the tasks and adjusted in the execution sequence via drag-and-drop. Furthermore, the GDS in-ports and out-ports can be assigned to the in-ports and out-ports of the programs. Naturally, PC Worx Engineer can also be used for programming in IEC 61131. 01 The AXC F 2152 PLCnext controller for the Axioline I/O system is consistently designed for maximum performance, easy handling, and for use in harsh industrial environments Solve diverse tasks flexibly As an essential feature of the PLCnext Technology, the freedom to realize the task with the user’s preferred tools has been consistently transferred to the entire system. If, for example, a function, a protocol, or a programming language is missing, the user can integrate or incorporate these himself without having to go through Phoenix Contact as the controller provider. This is only possible if not everything is encapsulated by runtime environments and the user can work directly with a well-known, widely used operating system. For the high-level-language programmer, it is simple to implement an MQTT protocol stack, for example. Other users from the Early Adopter Community have realized applications using the OpenCV library for image and video analysis as well as for object recognition. Furthermore, PLCnext Technology is coupled with Alexa, the digital assistant from Google. Other users use the platform outside of the real-time environment, and therefore without the Execution and Synchronization Manager, in order to be able to port third-party runtime environments and applications to it. These include a connection to Redis databases or the integration of Java Runtime in order to be able to program in Java. One Early Adopter implemented Node.js in order that he can realize web-based automation applications. The integration of other PLC runtime environments is also feasible. It therefore remains to be seen what further ideas users will realize with PLCnext Technology and in which direction the controller market will develop. All interested parties are invited to join the PLCnext community and discuss their projects with the community participants. Secure transmission of all data IT security is an important subject that must be considered with candor. This subject was the central focus in all area of the development of PLCnext Technology – both for the hardware and the software in the form of the operating system and the runtime supplied. Therefore, all communication channels to the PC Worx Engineer engineering tool are fully encrypted. Furthermore, the integrity of the engineering system information is validated by the WORLD OF INDUSTRIES 5/2018 15

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