Two worlds converging

With the introduction of specific solutions for the process technology market, Beckhoff is not introducing new components, but bringing together two automation concepts that for decades have been developed separately, yet side-by-side. While traditional PLC-based systems were optimised predominantly for short cycle times as a replacement for complex relay technology in machine controls, Distributed Control Systems (DCS) for classic Proportional Integral Derivative (PID) closed-loop control focussed mostly on scalability and system integration.

Driven by customer requirements and technological progress, both DCS and PLC have advanced and increasingly converged over the years. As a result, PLC systems have acquired ever more extensive visualisation systems. These are very similar to those that process engineers have used from the start and are implemented to manage many wide-ranging and complex processing workflows.

DCS, on the other hand, were optimised with regard to their performance and cycle times. Improvements such as these help accommodate even highly time-critical processes and equip process plants for safety-related requirements such as emergency stops and fire protection.

Growing requirements bring separate worlds together

The systems also converged in terms of scalability. DCS, which were designed from the start for large installations with tens of thousands of I/Os, were successful with simple engineering and retrofit capabilities. However, for today’s PLC-based systems, even I/O points in the high five digits don’t pose a challenge anymore. In addition, modern engineering environments like TwinCAT 3 software, feature a range of libraries and plenty of function blocks so that even highly complex closed-loop control structures can be designed quickly and reliably.

Developments regarding system architectures also deserve special attention. DCS focussed almost from the start on distributed I/O chassis, for example. These systems can collect data from areas exposed to explosion hazards with little wiring complexity and accommodate installations that are spread over large areas. PLC-based systems, on the other hand, initially concentrated on self-contained machines in small areas.

This has changed as simple machines have evolved into highly complex production lines within tightly networked plants, and operators have become more interested in using distributed peripherals that can be linked to fast fieldbus systems and deliver the bandwidth needed to accommodate the resulting flood of data. As a result, systems that can offer distributed intelligence, like the DIN rail-mountable Embedded PCs in the CX series from Beckhoff, are now a prevailing option, enabling direct connection of the EtherCAT based I/O system. In addition, deploying EtherCAT communication throughout allows operators to implement time- critical and highly synchronised control processes across distributed production steps. This includes the ability to integrate with central production control systems, and to perform data analysis and optimise processes.

PLC system offers maximum innovation potential

In terms of system architecture, the developments already mentioned have made PLC systems similar to the remote I/O systems that users are familiar with from the process control field. Especially in the context of Industry 4.0 concepts, the PLC approach has proven to be an innovation driver and has taken on a highly advanced structure that is superior, particularly in terms of performance.

It is above all the vision of the Internet of Things (IoT), which has led PLC-based systems to take on some characteristics of DCS in the past few years, especially in terms of integration capabilities. This, in turn, has increased support for mature protocols that offer cross-system data exchange, for example based on OPC Unified Architecture (OPC UA), but also for communication between the supervisory control level and the cloud through protocols such as Message Queuing Telemetry Transport (MQTT) and Advanced Message Queuing Potocol (AMQP).

While machine builders use these capabilities to implement the Industry 4.0 concept in its totality, process engineers require fully integrated solutions for a variety of reasons. They must cover all hierarchy levels ranging from data acquisition in hazardous areas to remote diagnostics of globally distributed systems via centralised process control systems. The goal is to reduce the required number of operators and maintenance staff. While this reduces costs, it also opens up new opportunities to make systems more efficient and reliable through the use of extensive diagnostics and analytics tools.

Open and modular automation technology as a complete solution

With PC-based control, Beckhoff offers an automation toolbox to implement all these requirements in an integrated solution. Through the addition of specific innovations for process technology applications, process engineers now have access to the same automation system that has long been proven in machine design and factory automation.

The openness of the PC-based control concept deserves mention, as support for all major bus systems allows the easy integration of Beckhoff controllers into existing architectures. Also, long-term product availability and backward compatibility provides the best possible investment protection and ensures spare parts supply. Even first-generation EtherCAT components can communicate with the latest product introductions. Benefits like these make it easy to upgrade existing systems, for example by adding cloud connectivity and IoT functions.

The benefits of integrated and open automation systems from Beckhoff become especially apparent when designing new plants. On the field level, the use of ELX-series EtherCAT Terminals for the direct connection of intrinsically safe field devices enables reductions in space requirements, and therefore, cost requirements. In addition, the elimination of the need for separate safety barriers delivers advantages with regard to installation and diagnostics. DIN rail-mountable embedded PCs from the CX series, equipped with up to 12 CPU cores, make it possible to distribute the execution of even the most complex control tasks with their high processing performance. Comprehensive product certifications ensure compliance with explosion protection requirements and enable installation in close proximity to the actual process. On the control level, the finely scalable portfolio of industrial PCs from Beckhoff enables custom-tailored solutions that can not only perform a range of control tasks, but also provide integration into process control systems. Support for many standards and protocols ensures cross-system data communication on both the higher-level control and field system levels.

The advanced TwinCAT HMI software solution enables the implementation of visualisation tasks according to the highest standards for efficient and reliable plant operation. In addition, the responsive TwinCAT HMI runs just as well on mobile devices as on industrial control panels and panel PCs. For process visualisation and control in hazardous areas (Zone 2/22), specific devices are available in the form of the CPX panel series with state-of-the-art, multi-touch technology and robust aluminium enclosures.

With the range of TwinCAT functions available, engineering for the plant operation and data transmission to a higher-level control system or cloud services become intuitive processes. Many diagnostic options and interfaces, such as the TwinCAT FDT container for integrating field device drivers (DTM), ensure quick and productive commissioning and easy access to the world of Beckhoff control technology. The integrated Beckhoff automation toolbox “for both worlds” is up to the task whether the requirements originate in the discrete, or in the process automation landscape.

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