Legacy distributed control systems deliver reliability for continuous or batch manufacturing processes that require operating many interdependent systems for long periods, providing plantwide process control, supervision and redundancy.

Operators can centrally oversee and optimize systems and react to issues without shutting down the entire operation.

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The ability to have oversight and limit the effects of problems to maintain uptime and throughput made it a natural choice for pharmaceutical production, refining, semiconductor manufacturing, and many other processes with strong interactions between units, large numbers of analog control loops, and other high-consequence operations that could suffer safety, environmental, or product failures if control is lost.

Legacy DCS solutions offered advantages over contemporary PLC-only controls by delivering built-in application-specific safeguards, alarm management, operator visibility and deterministic control designed to provide auditable, repeatable process execution and operate reliably for decades.

This level of redundancy has entrenched proprietary DCS in many operations. As these systems have aged, and supporting and maintaining them has become more difficult, as decades-old proprietary systems can be difficult or impossible to source replacement components.

Because legacy DCS deployments were designed as comprehensive proprietary systems, they limit manufacturers' ability to scale, or even simply maintain, their current production systems.

This “vendor lock-in” is a substantial single-source risk for manufacturers if critical parts or replacement equipment cannot be sourced.

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In addition, manufacturers can’t afford to shut down existing processes, and the time and cost of revalidating wholesale replacement of production equipment make upgrading prohibitive.

The proprietary nature of these systems has traditionally made it difficult or impossible to integrate third-party equipment. DCS data is typically exposed through proprietary systems, which can make it difficult to access the high-frequency, contextualized data manufacturers need to integrate new equipment.

As a result, moving to new production systems, integrating modular/agile processes, or simply scaling up capacity can be costly and risky.

Communication is key

Building a bridge to safe, modular upgrades and maintenance for legacy DCS systems is possible. It requires a high-level view of how hardware and software work together in legacy systems, and how standards-based solutions can create universal translation layers for data and controls.

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Data can be one of the most confounding issues in proprietary systems. A data orchestration layer uses edge computing devices to standardize, tag, and contextualize data from different processes and systems, enabling real-time analysis and information sharing.

Unified data systems let proprietary equipment share data through the translation layer with new equipment, enabling seamless communication of upgraded or replacement components within proprietary systems. A data orchestration layer is more than a unified database; it translates and delivers contextualized data where it is needed, in real time.

The data unification layer works in conjunction with a software-abstracted control layer. Software-abstracted controls enable rapid process changes, dynamic scaling and flexible automation by eliminating the need for machine-specific custom coding. The unified data architecture works with software-abstracted controls to facilitate robust machine and process analysis and process portability.

Module-type-package is an industry standard for equipment integration with higher-level control systems, providing a standardized description of functions and elements. Machines designed for MTP communication easily integrate into existing systems and communicate with the control layer.

That’s why standards-based hardware is promoted as “plug-and-produce.” Standards-based, open-architecture automation supports low-cost process changes while reducing single-source vendor risk.

By enabling real-time translation at the edge that connects the legacy DCS to the abstracted MTP layer, manufacturers can leverage the flexibility of modular manufacturing while maintaining their legacy DCS.

The MTP standard provides a vendor-agnostic description of equipment behavior to the control layer, standardizes the control-programming architecture, and allows equipment to be introduced, removed, or reconfigured without rebuilding automation or orchestration controls.

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The enhanced portability of controls, enabled by abstracting module behavior, streamlines the introduction of new components or the augmentation of processes, something frequently needed in a legacy DCS that was previously extremely expensive or impossible.

The combination of a data orchestration layer and a software-abstracted controls architecture that supports standards-based hardware lets manufacturers address obsolescence in vendor-locked deployments.

Dynamically decoupling DCS control logic within the software abstraction layer, and contextualizing and translating information streams for the data orchestration layer enables system standardization, allowing manufacturers to integrate new vendors, parts and equipment into legacy systems at lower commissioning cost.

This means a third-party OEM can quickly and cleanly integrate into the existing DCS while employing their own preferred PLCs, controllers or motion systems.

The data orchestration layer ensures process, batch, and state information is portable across historians, MES and other platforms, empowering analysis and decision-making.

Unlike legacy DCS, where control, data and HMI changes are often inseparable, this approach also minimizes validation risk when making changes, since the primary impact of new hardware or vendors falls on the software-abstracted layers, not the broader system.

Decision-makers are in the business of mitigating risk in manufacturing operations. That priority has led many to avoid upgrades and changes that could create unexpected downtime during commissioning.

Over time, as systems age, that risk profile changes. Single-source risk in aging proprietary systems consistently grows. Market demands are constantly evolving and require process agility. Advances in automation implemented in greenfield facilities require upgrades in legacy operations to stay competitive.

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By creating a unified data orchestration layer and software-abstracted controls, manufacturers can “future-proof” processes against obsolescence.

This approach lets manufacturers integrate standards-based or proprietary components into existing systems as needed, while maintaining the reliability and precision of their existing DCS deployments, delivering process agility and mitigating the growing risk of unexpected downtime as the supply of legacy components and spare parts dwindles.

Manufacturers don’t need to choose between maintaining legacy proprietary systems and replacing them entirely with expensive new systems.

A software-abstracted controls layer, and unified data orchestration layer powered by edge computing enable seamless integration of legacy hardware with new sensors, devices and automation.