When Should You Consider Upgrading or Replacing an Obsolete Legacy PLC System?

Key Takeaways

Retaining legacy PLCs seems frugal but hides costs in downtime and inefficiency. Key risks include frequent failures, scarce parts, severe cybersecurity vulnerabilities, and poor compatibility, which blocks Industry 4.0 integration. Upgrading boosts output, increases uptime via better diagnostics, and provides robust security. Signs of obsolescence include being over a decade old, performance degradation, and inability to expand. A proactive upgrade is a strategic necessity to prevent future emergencies.

Is your factory still running on a PLC from ten or twenty years ago? While it may seem thrifty, you're missing out on the speed, data, and security of modern controllers. Keeping that legacy system could be costing you more than you think in lost efficiency and surprise downtime. Here, we identify the clear signs your PLC is outdated, the advantages of upgrading, and how to make the transition smoothly.

Key Risks of Using an Obsolete PLC System

It may seem OK to keep an old PLC until it breaks down. Operating antiquated equipment carries actual hazards that can accumulate over time and cause your facility to experience unexpected and costly issues.

Frequent Failures and Costly Downtime

PLCs' components deteriorate with age, resulting in more frequent and unpredictable failures. Every time a PLC malfunctions, your production line may come to a complete stop. This unscheduled downtime is quite costly, both in terms of lost productivity and labor expenses, while your team frantically attempts to resolve the problem. In contrast, a contemporary system is constructed with more dependable parts and provides sophisticated diagnostics to identify issues before they result in a shutdown.

Scarce Spare Parts and Manufacturer Support

The inability to locate replacement parts is one of the main red flags of an outdated PLC. Older models eventually cease to be produced and supported by manufacturers; this is known as "End of Life." You might have to pay inflated fees, wait a long time for a replacement, or look for used parts from dubious third-party dealers when a component fails. This puts you in a risky position where a minor hardware malfunction could cause your business to halt operations for a long time. By upgrading, you may be confident that trustworthy suppliers will provide you with easily accessible parts.

Major Cybersecurity Weaknesses

Legacy PLCs were not built for the connected world of today. Since the manufacturer no longer provides security updates, the majority are easy targets for cyberattacks. An enormous safety and financial responsibility could result from a security breach that gives hackers access to private company information, interferes with business operations, or even takes over your equipment. Modern PLCs are made with the latest cybersecurity standards in mind, and they are patched frequently to shield your facility from evolving threats.

Poor Compatibility and Integration

Outdated PLCs have trouble connecting to contemporary IT networks, software, and equipment. You are unable to benefit from Industry 4.0 technologies such as remote monitoring, enhanced data analytics, and the Industrial Internet of Things (IIoT) because of this incompatibility. Your outdated system acts as an anchor, preventing you from utilizing potential advancements in scalability, data collection, and efficiency that your rivals may be employing.

The Top Benefits of a Modern PLC Upgrade

A PLC upgrade does more than just prevent breakdowns. It gives your operations a real boost in performance and prepares you for new challenges.

Enhanced Output and Speed

PLCs nowadays have greater memory and faster processors. This enables them to manage intricate plans and carry out instructions more quickly, which directly boosts the productivity and efficiency of your plant. A contemporary controller is capable of handling your current workload with fewer mistakes and is prepared for any additional automation projects you may add in the future.

More Uptime and Faster Fixes

New PLC systems are built for high reliability. Many support backup processors and redundant power supplies, so the system keeps running even if a component fails. This drastically reduces expensive downtime. They also include better diagnostic tools that pinpoint problems, so technicians can find and fix them faster. Just as important, spare parts are readily available and supported by the manufacturer.

Modern Security and Safety

Upgrading is a key step in protecting your plant. To protect against emerging attacks, new systems are regularly updated and developed using the most recent cybersecurity standards. This helps you comply with safety rules and protects your operational data. Additionally, many come with integrated safety features that improve the safety of your staff and equipment.

Easier Connections to New Technology

A contemporary PLC serves as the central point for the technologies in your factory. It readily links to a variety of gadgets, including sophisticated sensors, robotic arms, and business applications. This connectivity allows you to collect the real-time data necessary for smart manufacturing with cloud PLCs, enabling you to enhance operations by forecasting maintenance requirements and monitoring production effectiveness. An upgrade guarantees that if your company expands, your facility can accommodate additional equipment.

How to Know Your PLC System is Obsolete

You will likely not get a formal expiration date for your PLC. Instead, you need to look for specific clues that your system is falling behind and becoming a liability for your plant.

• Check Manufacturer Status: The clearest sign is when a manufacturer officially designates a PLC series as "Discontinued" or "End of Life." This means they will no longer sell, support, or provide updates for it.
• Look at the System's Age: If your PLC system is over a decade old, it is almost certainly lacking in processing power, memory, and connectivity compared to modern alternatives. Technology has advanced significantly, and an older system is holding you back.
• Notice Performance Problems: Are you experiencing more frequent breakdowns, slower processing speeds, or random shutdowns? These are classic signs that the hardware is aging and can no longer keep up with production demands.
• Review the Software: Many legacy PLCs run on or are programmed with software that relies on outdated operating systems like Windows 7 or even Windows XP. This is a massive security risk and makes the system difficult to maintain.
• Struggle with Spare Parts: If your maintenance team reports that finding replacement parts is becoming a difficult and expensive scavenger hunt, your system is obsolete.
• Find You Cannot Expand: If your PLC lacks the memory, processing power, or input/output (I/O) capacity to add new equipment or implement a process improvement, it is time for an upgrade.

Common Challenges to Plan for in a PLC Upgrade

An upgrade is a smart move, but it is also a major project. Being aware of the common hurdles can help you plan effectively and ensure the transition goes as smoothly as possible.

Minimizing Disruption to Operations

The biggest concern for any facility is downtime. A "rip and replace" approach, where you shut everything down, is often not feasible. A phased migration is a popular strategy, where you upgrade one section or machine at a time. This approach minimizes disruption and spreads the cost over time, but it requires careful planning to ensure both old and new systems can work together during the transition.

Securing the Budget and Justifying the Cost

PLC upgrades require a significant initial investment. To get approval, you need to build a strong business case. Focus on the return on investment (ROI) by calculating the costs of downtime, high maintenance, and scrapped product caused by the old system. Contrast this with the financial gains from increased productivity, reduced errors, and lower operational costs that a new system will provide.

Managing the Technical Migration

The upgrade process is technically complex. It involves more than just swapping out hardware. You may need to rewire I/O points, convert old programming code to the new platform, and configure new communication networks. Legacy code is often poorly documented, which adds another layer of difficulty.

Finding the Right Expertise

As PLC systems become obsolete, so does the knowledge required to maintain them. It can be difficult to find engineers or technicians who are experienced with your specific legacy platform. For this reason, many companies choose to work with an experienced integration partner who specializes in PLC migrations to manage the project and train the staff on the new system. Make sure they are proficient in modern PLC programming.

3 FAQs About PLC Upgrades

Q1: I can still use my old PLC. Why should I get a new one?

A: A legacy PLC probably has hidden vulnerabilities even if it appears to be operating well. A failure is a matter of when, not if, due to the absence of security updates, the scarcity of spare parts, and the incapacity to connect with contemporary technology. A proactive upgrade prevents a future emergency.

Q2: What should I do to start planning an upgrade?

A: Start by evaluating your current system in detail. Keep a record of all your communication networks, hardware, and software. Your migration plan will be built on this assessment, which will assist you in defining the requirements for a new system and identifying important hazards.

Q3: Should I carry out the upgrade in stages or all at once?

A: Because it reduces operational disturbance and spreads the expense over time, a phased migration is frequently the recommended approach. The optimal strategy, however, depends upon the particular requirements of your facility, production schedules, and system complexity.