Upgrading a Programmable Logic Controller (PLC) is more than a hardware change—it’s a strategic move to improve performance, reduce downtime, and future-proof operations. If your plant still relies on outdated PLCs, now is the time to consider a PLC upgrade to stay competitive in the fast-evolving world of industrial automation.

In this guide, we’ll walk you through what a PLC upgrade involves, signs it’s time to upgrade, key benefits, cost considerations, steps in the upgrade process, and answers to common questions.

What Is a PLC Upgrade?

A PLC upgrade is the process of replacing or enhancing an existing programmable logic controller with a newer, more advanced version. This may include updating the CPU, input/output (I/O) modules, communication protocols, programming software, and even connected HMI (Human Machine Interface) systems.

Whether it’s a partial modernization or a full system overhaul, upgrading your PLC helps ensure seamless integration with modern technologies such as Industry 4.0, remote monitoring, and predictive maintenance.

Why Consider a PLC Upgrade?

1. Obsolete PLC Systems Pose Risks

Older PLC models may no longer be supported by manufacturers. This means:

  • No security patches

  • Difficulty finding spare parts

  • Incompatibility with modern software

  • Increased system failures

2. Downtime Costs Money

Unplanned downtime can cost thousands—or even millions—per hour. A modern PLC system improves reliability and prevents costly shutdowns.

3. Improved Speed & Efficiency

Modern PLCs process data faster and can handle complex automation tasks, leading to better throughput and efficiency.

4. Enhanced Connectivity

New PLCs support Ethernet/IP, Modbus TCP/IP, and other protocols for seamless integration with MES, SCADA, and cloud platforms.

5. Cybersecurity Upgrades

Outdated PLCs are vulnerable to cyberattacks. Upgrading enhances your industrial cybersecurity posture.

Signs It's Time to Upgrade Your PLC

Look for these red flags indicating a PLC upgrade is overdue:

  • Frequent system crashes or unpredictable behavior

  • PLC manufacturer no longer offers support or firmware updates

  • Lack of spare parts in the market

  • Limited or no Ethernet communication

  • Incompatibility with new sensors or HMI devices

  • Difficulty finding programmers or integrators who can work with the system

  • You’re still using ladder logic only with no support for modern programming standards

Benefits of a PLC Upgrade

Here are the top benefits of upgrading your PLC system:

✅ Higher System Reliability

Newer hardware is more robust, reducing the risk of failure.

✅ Greater Scalability

Modern PLCs are modular and can easily scale with your operation.

✅ Advanced Diagnostics

Built-in diagnostic tools help reduce troubleshooting time.

✅ Better Data Access

Real-time access to machine data enables proactive decision-making.

✅ Future-Ready Automation

Modern PLCs support integration with IIoT devices and cloud services.

Step-by-Step PLC Upgrade Process

A structured approach ensures a smooth transition with minimal downtime. Here's how a PLC upgrade typically unfolds:

1. Assessment & Planning

  • Inventory current PLC hardware and software

  • Evaluate system performance and gaps

  • Identify end-of-life (EOL) components

  • Define upgrade goals (performance, security, connectivity, etc.)

2. Choose the Right PLC Platform

Pick a new PLC that meets your current and future needs. Consider:

  • Brand compatibility (Rockwell, Siemens, Mitsubishi, etc.)

  • Number of I/O points

  • Communication protocols

  • Software platform support

3. Design & Programming

  • Create an updated logic design

  • Convert or rewrite ladder logic/code

  • Design new I/O maps if needed

  • Test offline simulations to validate behavior

4. Hardware Installation

  • Mount and wire new PLCs

  • Connect new I/O modules and HMIs

  • Update network settings

5. System Testing & Commissioning

  • Perform I/O checks

  • Load and run the control program

  • Test interlocks and safety logic

  • Monitor for unexpected behavior

6. Training & Handover

Train maintenance and operations teams on the new system and software.

7. Documentation & Support

Ensure all new logic, wiring diagrams, and user manuals are updated and backed up.

PLC Upgrade Cost Considerations

Upgrading a PLC can range from a few thousand dollars to several hundred thousand, depending on system size and complexity. Cost factors include:

  • Hardware: New PLCs, I/O modules, HMIs

  • Software: Licensing for PLC programming environments

  • Engineering Time: Design, programming, testing

  • Downtime: Production loss during installation

  • Training: For operators and maintenance staff

Tip: Many facilities opt to upgrade during scheduled shutdowns to avoid production losses.

Choosing the Right PLC for Your Upgrade

Popular Brands for Modern PLCs:

  • Allen-Bradley (Rockwell Automation) – Excellent for North American plants

  • Siemens – Known for global support and robust features

  • Mitsubishi Electric – Cost-effective with reliable hardware

  • Schneider Electric – Strong in building automation and industrial control

Make sure to check backward compatibility and integration with your existing systems.

Common Challenges During a PLC Upgrade

Be aware of these pitfalls and how to avoid them:

  • Data loss – Always back up existing logic

  • Wiring mismatches – Double-check I/O mapping

  • Undocumented code – Allocate time for reverse-engineering old logic

  • Inadequate testing – Simulate thoroughly before deployment

  • Poor training – Ensure your team knows how to operate the new system

How Long Does a PLC Upgrade Take?

The timeline varies by project scope. A small machine-level upgrade might take 2–3 days. A plant-wide upgrade may take several weeks. Proper planning can significantly reduce installation time.

Call to Action: Ready to Upgrade Your PLC?

A PLC upgrade is one of the best investments for your facility’s performance, reliability, and long-term growth. Don’t wait for failure—modernize now and unlock the full potential of your automation systems.

Get in touch with our PLC upgrade experts today for a free consultation. Whether you're updating a single controller or planning a full system overhaul, we can help you design and implement the best solution.

FAQ: PLC Upgrade

What is a PLC upgrade?

A PLC upgrade replaces old programmable logic controllers with modern ones to improve system performance, reliability, and connectivity.

How much does a PLC upgrade cost?

Costs vary widely based on system size, but a typical small to mid-size upgrade ranges from $5,000 to $50,000.

How do I know if my PLC is obsolete?

If your PLC is no longer supported by the manufacturer, lacks Ethernet connectivity, or often fails, it’s likely obsolete.

Can I upgrade my PLC without shutting down the entire system?

In some cases, yes. With modular systems or redundancy, upgrades can be done in stages to minimize downtime.

What’s the best PLC brand for upgrades?

Allen-Bradley and Siemens are top choices, but the best brand depends on your industry, existing systems, and technical support availability.

Final Thoughts

A well-planned PLC upgrade can eliminate downtime, reduce maintenance costs, and prepare your facility for the future of smart manufacturing. With the right team and tools, you can upgrade efficiently and confidently.

Don’t wait until your PLC fails—modernize now for a smarter tomorrow.