The evolution of the DCS: meeting the needs of the digital revolution

As digital technologies increasingly find their way into industrial applications, a new generation of distributed control system is needed.

The growth of automation is making a world of difference in industrial applications, enabling an expanding range of production tasks to be handled and executed more efficiently, productively and safely.

Much of the hard work entailed in making the decisions that make automation possible is carried out by distributed control systems. Combining a series of control loops regulated by distributed process controllers linked into a single operator platform, distributed control systems have proven highly effective in managing core operational, maintenance and safety functions in a wide range of process and plant applications.

By enabling large and complicated control functions to be managed in a single environment, distributed control systems offer several advantages:

• Safety and system availability: With their inherent built-in redundancy, distributed control systems enable safe and disruption-free operation in the event of a problem.
• Reduced downtime: By monitoring all aspects of plant performance, distributed control systems can highlight when and where problems are likely to occur, allowing timely action to be taken. Automated decision-making also reduces the potential for operator error, such as missing, misinterpreting or ignoring an alarm condition.
• Visualisation: When linked into an operator platform, data from distributed control systems covering a few hundred to potentially thousands of tags or assets can be presented via a HMI to provide a detailed overview of plant conditions. Functions such as data logging and alarm management help to provide additional information that the operator can use to make informed decisions.
• Scalability: A key benefit of distributed control systems is their scalability. Systems can be adapted to meet changing requirements such as extra control operations, with the ability to add extra control or process units when needed. Compared to PLCs, which have limitations on I/O, distributed control systems offer a much easier path, with I/O capacity able to be expanded by adding extra modules to the controller.
• Security: With multiple layers of security for different levels of access, distributed control systems offer a secure platform for handling key factory automation control functions.

Keeping up with the future: why adaptivity is key

Keeping pace with increasingly complex process demands requires control systems that can run processes seamlessly and effectively while minimising complexity for the user. They must also facilitate effective collaboration between people, systems and equipment to ensure maximum productivity.

Digitalisation is the key to unlocking the functionality required to power the factory of the future. While the distributed control system has always been connected, the rules of that connectivity have traditionally placed a master controller at the top governing an entire process from start to finish. With modular automation, complex processes are broken down into modular building blocks that can be added, subtracted or amended discretely without affecting the wider process. By removing much of the time, cost and effort involved in systems engineering, the modular automation concept provides businesses with unprecedented agility and flexibility. Modules are equipped with their own intelligence and can function autonomously without the need for executive control yet can also plug into the wider system with ease.

With modular automation, complex processes are broken down into modular building blocks.

The flexibility that this creates cannot be understated. The cost and criticality of distributed control systems prohibits just replacing them every time something new comes along or when additional functionality is required. As such, the modern distributed control system must be capable of constant change, with the flexibility and adaptability to meet not only current needs, but also the needs of tomorrow. This is where a modular approach brings particular benefits, as elements of the process can be changed or upgraded without having to replace the entire system, essentially futureproofing the DCS against new developments in the market.

Connected systems

Smart devices and systems, connected via the cloud, are a key enabler for this approach, opening a vast range of opportunities for improving process reliability and efficiency. Real-time analytics on the efficiency of subsystems or even individual components can be accessed, monitored and actioned in near real time, even from remote locations. Furthermore, because the system is modular, potential issues can be detected earlier, with any affected modules able to be removed from the wider process and worked on if needed without incurring plant downtime.

Connected systems are crucial if users are to unleash the potential of the modern DCS. As such, an open approach to communications and compatibility is key to driving innovation and avoiding the risks of proprietary systems that can lock users into certain manufacturers, potentially exposing them to supply issues, obsolescence or a lack of timely access to technical and engineering support. Automation manufacturers recognised this problem some years ago, resolving to work together to develop standards that would result in cross-compatibility between devices and components.

An open platform for change

NAMUR Open Architecture (NOA) was established in 2016 and sets out a vision for how to apply digital technologies to control systems in process-oriented industries. This vision includes various guiding principles to ensure data is easily and securely usable for plant and asset monitoring as well as optimisation by maintaining shared standards that all manufacturers signed up to the agreement must adhere to. These principles include:

• No compromise on plant safety and plant availability.
• Open interface between ‘Core Process Control‘ and ‘Monitoring and Optimisation’.
• A consistent approach for new and existing production plants.
• Agile implementation based on existing standards.
• Automation security must be an integral design aspect (security by design).
• Usability, reduction of complexity and economic efficiency are the key success factors.
   

NOA effectively adds a layer to a DCS that allows extra functions to be added by providing an open and secure environment for integrating IT components from the field up to the enterprise level. Compared to the somewhat closed system design of older generations of DCSs, and as an improvement to the modern, more open yet slow-to-advance automation platforms, the NOA principles provide the flexibility for distributed control systems to adapt more rapidly to new technologies.

With this new approach, operators can extend the capabilities of their control systems to include new functions such as asset and device management, optimisation and planning, without impacting on the core functions of the distributed control system itself and without the time or risks previously associated with making changes or upgrading.

A good example is the application of edge computing and the cloud in helping companies to increasingly explore the benefits of IIoT-enabled sensors. These devices produce a huge amount of data about processes — temperatures, pressures and the levels of liquids in a vessel, to name a few — all of which needs to be gathered, processed and analysed. In the past, a lot of this data was left untended and not utilised, with companies lacking the ability to easily analyse it or share it between individuals, departments or multiple sites.

By enabling edge and cloud technologies to be easily integrated into the distributed control system, the NOA approach presents the possibility for users to fully unlock the possibilities of Industry 4.0 by making valuable operational data readily and securely accessible as and when required to allow informed decisions and actions.

It will also provide greater flexibility in the way that solutions are implemented, enabling a shift from traditional buying of systems to usage-based ‘pay-as-you-go’ software subscriptions. This approach always brings new possibilities when it comes to business models and how applications, and eventually the DCS itself, is purchased, from buy it upfront to software as a service.

Building on these efforts is the next step in the evolution of the distributed control system. Leveraging digital technologies such as edge computing and the cloud require collaboration, particularly given the complexity of the technologies and systems involved. It also means a focus on what the end user needs, and not just what the automation manufacturer wants to or is able to offer. For instance, smart sensors can automatically transmit vast amounts of process data continuously to provide feedback on machine and process performance.

Putting the operator at the fore

While the technologies covered offer unprecedented access to a multifaceted range of process and operational data, there is a limit to how much data a human operator can evaluate at once. As such, any distributed control system must be able to not only turn all this data into useful information but also provide the operator with what they need to know in a way that they can easily understand and respond to. The modern distributed control system makes this possible by enabling the improved flow of IoT data, ensuring that the right information gets to the right person at the right time, allowing them to take appropriate and timely action while facilitating more effective and streamlined decision-making.

Addressing sustainability

With sustainability and the drive to net zero now high on the boardroom agenda, innovations achieved by the distributed control systems of the future will help advance both operational efficiency and productivity, while improvements in efficiency can help to reduce emissions and raw material use.

Summary: The best is yet to come

Process automation systems of the future will empower industries to compete in a fast-changing world by delivering adaptable, reliable, integrated, modular and secure automation solutions. Collaboration will be key, and the result will facilitate better integration and ease of use for operators, while creating an ecosystem whereby the DCS will adapt to meet any challenge that arises in the future.

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