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Open, flexible, and future-proof controller generation

Today, there are more networked devices than there are people, and the trend is accelerating. The traditional automation pyramid is being replaced by networked structures and cloud technologies. The requirements on the security, openness, and interoperability of these systems are increasing.

“Innovation cycles are being shortened and different development tools and processes are needed to meet the increasingly demanding time to market,” said Roland Bent, chief technology officer at Phoenix Contact’s head office in Germany. But what does this mean for manufacturers and users? And what opportunities could arise from such technological developments?

Alongside the classic IEC 61131-3 languages – i.e. function block diagram (FBD), ladder diagram (LD), sequential function chart (SFC), and structured text (ST) – programmable logic controllers (PLCs) will be programmed increasingly in high-level languages such as C++ and C#.

Model-based programming – for example Matlab Simulink – is being used for control technology applications. Automation engineers not only have to take these languages, which are often new to them, into consideration but, due to Industry 4.0 and the Internet of Things (IoT), must also realise additional requirements in the field of connectivity. These developments are accompanied by the fact that data security is becoming more important.

In order to be able to embrace these changing framework conditions, Phoenix Contact introduced the term PLCnext Technology and presented a concept that intends to answer technological questions that arise within the context of current and future applications with the highest possible level of openness.

“Until recently, controller programming – assuming it is deterministic in principle – was only possible using defined PLC programming languages,” said Bent. “Here, PLCnext Technology simplifies the engineering as it represents an open platform on which multiple developers, from different generations and programming disciplines or domains, can work in parallel on one control program.”

The basis of PLCnext Technology is an intelligent layer between the application program and operating system, which all system components use to exchange data synchronously and in real time, and which also provides easy access to system services such as Ethernet sockets.

Due to their open interfaces, the user can use the intermediate layer to integrate and install their own programs (Apps) without problems and to communicate with all other system components and the operating system. This is true regardless of whether the programs are created conventionally in IEC 61131-3, in high-level language – such as C# or C/C++ – or via Matlab Simulink. The developer decides on the most suitable software tool for the relevant application or can even combine various tools.

While an IEC 61131-3 programmer can use the new PC Worx Engineer software, or generate and upload models directly in Matlab Simulink, a high-level language programmer can choose between Visual Studio and Eclipse. This means that every employee is developing in their preferred tool, which eliminates any costs for training in other programming tools.

A year after introducing PLCnext Technology to the market, Phoenix Contact created the first industrial controller that is based on that technology, the PLCnext Control (AXC F 2152). The PLCnext Control product family starts with a dual-core hardware architecture with 512MB memory and a system clock rate of 800MHz. In comparison to conventional PLC technology, this is impressive but that is not the core innovation. The current device from the PLCnext Control family has been tailored to the market for decentralised, modular small-scale controllers. PLCnext Control is based on an embedded Linux architecture, with a core that has been expanded to include real-time capability.

Linux operating systems offer advantages such as system integrity, stability, and secure communication, paired with optimal openness and flexibility. These failures can be utilised in industrial automation as well. Linux also offers the best portability to various hardware platforms and makes scaling, or the use of future processor architecture, possible.

The task-handling Execution Synchronisation Manager (ESM) of PLCnext Technology makes it possible to combine programs from a range of development environments with one another or within tasks, yet have them behave like homogeneous IEC 61131 code. This automatically makes high-level languages deterministic as well.

Task handling supports a mix of IEC 61131, high-level, and model-based languages. The second technological aspect is the consistency of the data of the process image. In PLCnext, this is handled by the Global Data Space (GDS). Using sophisticated mechanisms with internal port and data buffer structures, the GDS ensures that the individual program elements receive the precise and consistent data image that is crucial for running the respective program successfully.

An OPC UA server has been implemented, as well as system, user, and fieldbus managers, diagnostic loggers, trace controllers, PC Worx Engineer HMI, and automatic access to Proficloud. In addition, PLCnext Technology works with proven Proficloud services and also supports the integration of proprietary cloud solutions. This represents a step toward preventive diagnostics and IoT. Conventional fieldbus systems – such as ProfiBus, CAN, Modbus/RTU, and InterBus – as well as real-time Ethernet standards – such as ProfiNet and Modbus/TCP – are also supported. PLCnext Technology is consistently designed for the later integration of additional protocols so that users can respond flexibly to future developments.

Digitalisation in automation technology is not a new topic. Industrial control and communication technology has been digital for the past 30 years.

The new dynamic associated with this term is the comprehensive and ubiquitous intelligent networking of all things, products, machines, processes and people, combined with almost limitless computer power. PLCnext Technology provides the basis for automation solutions capable of meeting all the challenges of the digitised world

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