If you run a manufacturing facility in Wisconsin, chances are some of your equipment is still running on legacy PLCs like Allen-Bradley SLC, Omron C-series, or even Texas Instruments models from decades ago. At first glance, if the machine still works, it might feel like there’s no urgency to upgrade. But the real costs of downtime, scarcity of parts, and cybersecurity risks often far outweigh the upfront investment of a modern PLC conversion.
Why Old PLCs Put You at Risk
1. Scarcity of Parts and Support
Many legacy PLCs are officially discontinued.
Used modules may only be available on secondary markets — with no guarantee they’re reliable.
Engineers with experience programming these older systems are retiring, leaving fewer people able to support them.
2. Downtime is Expensive
A single unplanned line stoppage can cost $10,000+ per hour in lost production.
If your plant runs multiple shifts, every hour of downtime compounds labor costs, missed orders, and penalties.
Without a backup plan, replacing a failed PLC may take days or weeks.
3. Cybersecurity Vulnerabilities
Older PLCs were not designed with modern cybersecurity in mind.
No encryption, no role-based access, no VPN protection.
That leaves your plant vulnerable to ransomware and remote attacks.
The ROI of Planned PLC Upgrades
Upgrading doesn’t just avoid disaster — it pays back quickly:
Modern Spares Available: Parts are easier to source, keeping downtime low.
Future-Proof Programs: Ladder logic can be migrated and backed up for long-term use.
Energy Efficiency Gains: New PLCs often integrate with energy monitoring and SCADA dashboards.
Reduced Maintenance Calls: In-house staff can troubleshoot more easily with updated interfaces.
👉 Example: A foundry in Milwaukee upgraded a 25-year-old TI PLC to a modern Allen-Bradley CompactLogix during a holiday shutdown. Downtime was reduced from days (if a failure occurred) to just hours for any future service.
How to Plan Your Upgrade
Inventory Your Legacy PLCs
Identify which models are at or beyond end-of-life.
Assess Critical Machines
Prioritize lines where downtime would cost the most.
Schedule a Low-Impact Cutover
Plan upgrades during holiday or weekend shutdowns.
Secure Program Backups
Always create encrypted backups before and after the conversion.
Train Maintenance Staff
Ensure operators and technicians can handle basic troubleshooting.
Conclusion
Running on legacy PLCs is like running your business without insurance. The upfront cost of upgrading is always less than the financial hit of unplanned downtime. By modernizing your control systems, you safeguard production, reduce risk, and improve efficiency.
📞 Ready to discuss a PLC upgrade?
Call us at (414) 209-LINC or email [email protected]
to schedule a free consultation.
