At CORE Integrators, we enjoy sharing insights and ways to help our customers. Upgrades can range from updating a single processor on one piece of equipment to plantwide projects involving dozens of individual systems. We can also assist in mapping out a plan for plantwide upgrades across multiple sites. For example, one of our projects spanned eight facilities and included seventy systems.
Recently, we had the opportunity to sit down with Tim Alligood to discuss the challenges and considerations of upgrading legacy Rockwell / Allen-Bradley PLC systems, such as PLC-5 or SLC, to modern platforms like ControlLogix. Tim, one of our Solution Engineers and former Design Manager, shared his insights on using Rockwell’s hardware conversion kits to ease this transition.

Why Consider Upgrading Your Legacy Rockwell PLC System?
Legacy systems like the PLC-5 have been reliable workhorses for years, but their limitations are becoming more apparent. As parts become harder to source and technology advances, migrating to a modern ControlLogix platform offers better performance, scalability, and long-term reliability.
However, the path to modernization isn’t always straightforward, especially when minimizing downtime is a top priority.
The Pros of Using Rockwell’s Hardware Conversion Kits
One of the tools Rockwell provides to simplify this transition is the hardware conversion kit. Tim highlighted several key benefits:
Reduced Downtime for Changeover
The conversion kits are designed for plug-and-play functionality, utilizing the existing I/O module terminal swing arm. This eliminates the need to rewire all terminations, which can save a lot of time.
Reduced Wiring Errors
By reusing the original swing arm, you’re less likely to introduce wiring errors during the upgrade. This is especially important when downtime is costly, and accuracy is critical.
A Practical Short-Term Solution
For systems with high-density I/O modules or limited spare points, these kits can be a lifesaver. They allow you to upgrade functionality and reliability while planning a more comprehensive rewiring in the future.
The Trade-Offs to Keep in Mind
While the benefits are compelling, Tim also pointed out some challenges associated with using these kits:
Added Cost and Specification Complexity
The kits themselves add cost, and specifying the correct components requires careful planning. Mistakes in identification can lead to delays during installation.
Limited Flexibility
Conversion kits maintain the existing wiring layout, which might not align with your long-term goals. For example, you may want to consolidate or reorganize I/O to reduce space and material costs.
Potential Reliability Concerns
The original swing arms may already be worn or damaged, leading to connection issues. Troubleshooting these problems is more difficult because they’re enclosed behind the conversion kit’s cover plate.
Impact on Legacy Equipment Value
Once you use the conversion kit, you’re left with legacy PLC components missing their swing arms, which can reduce their resale or surplus market value.
Finding the Right Solution
When asked when these conversion kits are most effective, Tim shared his perspective “The best use case for these kits is when you need to upgrade quickly, either to add new functionality or address reliability issues, but don’t have the time or budget for a full rewire. In the long run, though, it’s often worth planning for a complete modernization.”
How CORE Integrators Can Help
At CORE Integrators, we have extensive experience with Rockwell PLC migrations. Whether it’s converting software, performing panel modifications, or helping you plan a phased upgrade, our team is here to ensure a smooth transition to modern automation systems.
Final Thoughts
Upgrading from a legacy PLC system to ControlLogix is a big step, and using Rockwell’s conversion kits can make the process easier. However, it’s essential to weigh the benefits against the challenges and tailor the solution to your specific needs.
Want to discuss your PLC upgrade options with our experts? Reach out to CORE Integrators today, and let’s explore the best path forward for your system.

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