The Case for Open PLC Architecture

Talking Points

Organizations are increasingly adopting open programmable logic controller (PLC) architectures to enhance flexibility and resilience amid unpredictable supply chains. Traditional closed systems, reliant on single vendors, have proven vulnerable to delays and disruptions, prompting a shift towards open systems that allow for component interchangeability from multiple suppliers.

• Open PLC systems facilitate integration through industry standards like OPC UA and MQTT, reducing training time for engineers.
• Modular designs enable gradual expansion and adaptation without halting projects due to unavailable components.
• Financially, open architectures allow companies to negotiate better pricing and align with trends like Industry 4.0 and the Industrial Internet of Things (IIoT).

This transition to open PLC architecture is crucial for businesses seeking to maintain operations and adapt swiftly in a rapidly changing environment.

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Programmable logic controllers (PLCs) are still at the heart of modern industrial automation. Whether it’s a manufacturing line or an energy system, PLCs keep things running accurately and efficiently. But the world around them has changed. Supply chains have become far less predictable, shaped by geopolitical tensions, pandemics, chip shortages and shifting trade dynamics. Because of this, the traditional “closed” approach to PLC systems is starting to show its limits.

More and more organizations are turning to open PLC architectures— not just because they’re technically appealing, but because they make strategic sense.

At a basic level, open PLC systems are built to be flexible. They’re designed so components from different vendors can work together, instead of locking you into a single supplier’s ecosystem. That flexibility is becoming incredibly valuable in a world where delays and disruptions are the new normal.

Why traditional setups are struggling

In the past, many automation systems were built around tightly integrated, proprietary PLCs. These systems often worked well—they were reliable, efficient and relatively easy to deploy. The downside? They tied everything to one vendor.

That wasn’t a big problem when supply chains were stable. But recent disruptions have exposed how fragile that model can be. Companies have faced long delays, sometimes months or even years, waiting for specific parts.

When you depend on one supplier, any delay can ripple through your entire operation. Production slows down, maintenance gets pushed back and expansion plans stall. For businesses running on tight schedules, that’s a serious risk.

How open architecture changes the game

Open PLC architectures tackle this problem head-on by removing vendor dependency. Instead of relying on one manufacturer, companies can choose from a wider pool of suppliers.

If one vendor can’t deliver a component, you can often source a compatible alternative. If hardware changes, your software can usually adapt without major rework. That kind of flexibility helps keep operations moving, even when supply chains don’t cooperate.

It’s not just about handling today’s disruptions, either. Open systems make it easier to adapt over time. You’re not locked into decisions you made years ago — you can evolve as conditions change.

The role of standards

A big reason open systems work is because of industry standards. Communication protocols like OPC UA and MQTT allow devices from different vendors to “speak the same language.”

This makes integration much simpler. It also means engineers don’t have to relearn everything when working with new equipment, which saves time and reduces errors— especially important when skilled workers are in short supply.

Another benefit: innovation. When more companies can build compatible products, you are sure to get a healthier, more competitive ecosystem and better options for customers as a result.

Modularity makes life easier

Open PLC systems are also modular, meaning they’re built from interchangeable parts. Instead of committing to one large, rigid system, you can build and expand step by step.

That’s a big advantage when supply is uncertain. If one component isn’t available, you can often move forward with alternatives and upgrade later. Projects don’t have to come to a standstill.

Over time, this also makes scaling easier. As your needs grow, you can expand your system without starting from scratch.

What about security

It’s fair to ask whether open systems are more vulnerable to cyber threats. They can be, simply because they’re more connected. But openness doesn’t automatically mean less secure. In fact, many open standards include strong built-in security features like encryption and authentication. And because these systems are more transparent, vulnerabilities are often identified and fixed faster.

The key is to be proactive—regular updates, network segmentation and continuous monitoring go a long way. When done right, open systems can be both flexible and secure.

The bigger picture: Cost and strategy

There are also clear financial benefits. With multiple vendors in play, companies can shop around, negotiate better pricing, and avoid the premium that often comes with proprietary systems.

Strategically, open architectures fit naturally with trends like Industry 4.0 and the Industrial Internet of Things (IIoT). As systems become more connected and data-driven, the ability to integrate different technologies becomes critical—and open platforms make that possible.

In terms of supply chains, all of this adds up to one thing: resilience. Companies can respond faster to disruptions and keep operations running, even when conditions change.

Looking forward

The move toward open PLC architecture currently being seen across the industry isn’t just a technical shift—it’s a response to a more uncertain world. Supply chains aren’t as predictable as they used to be, and businesses need systems that can adapt. Open architectures offer that flexibility. They reduce dependency, support innovation and help organizations stay agile.

Making the transition from closed to open takes planning, and in days gone by that would mean potentially months of engineering work. Today the tools available can help reduce that time and effort from months down to weeks saving the user so much making the payoff clear.

In a world where disruption is constant, resilience isn’t optional, it’s essential.

And openness is how you get there.

Paul DeJong is the founder of Northern Dynamics, a trusted Systems Integrator and official CODESYS Systems Partner. With a strong background in industrial automation and control systems, he leads Northern Dynamics in delivering innovative, efficient and future-ready solutions for clients across industries.

This article was originally written for automationmag.com.