Migrating a Legacy DCS: When and How

Migrating a Legacy DCS: When and How

An old DCS is not necessarily a bad DCS.

There are many older DCS operating without issue in plants around the world. Maybe you have one of them.

Still, I get this question almost every day: “How do I know it's time to migrate my DCS?” (And the follow up question, “And how should I do it?”)

Is it Time?

Let me address both. The numbers from ARC Advisory Group show that you're not alone:

  • 65 billion process automation systems are nearing end of life
  • 12 billion of those are 25 years old – or older
  • 20% of experts with these systems are retired or near retirement (and they're taking their process knowledge with them)
  • Third party contractors are required for support, and that creates greater risk

With these older systems, two issues are significant:

  • Lack of spares
  • Lack of knowledge

If you can get the parts, you still need someone knowledgeable to use them. And that's where the biggest risk comes in. A significant number of DCS experts are leaving the workforce without the adequate number to replace them – and if you are lucky enough to find an expert, there's still a lack of knowledge about older systems.

So, with these factors in mind, you realize it's time to migrate. But what's the best way for your situation?

The first hurdle is financial justification. That's where you might hit a wall called, “If it isn't broke, don't fix it.”

Remember: the economic picture is more than simply upfront expense. You need to look at overall costs – and benefits. Migrating to current technology gives you enhanced optimization capabilities, reduced lifecycle costs, increased yield and quality, and more data for faster decision making.

The Process Solutions User Group (PSUG) event, November 7-8 in Atlanta, GA, brings together a diverse gathering of professionals from every process industry around the globe to share common interests in learning about the latest process automation technologies. Register to attend.

Moving Forward: Your Choices

When I talk about migrating a legacy DCS, the options generally fall into two buckets: phased, or rip and replace.

What's best for you depends on your situation, because both present big plusses – and a few drawbacks.

Phased migration benefits:

  • Requires less downtime than a full rip and replace and may not completely shut down production
  • Can be funded with maintenance funds – depending upon the size of the project
  • Lower risk
  • Can be easily switched back to the legacy system as part of a contingency plan

Phased migration drawbacks:

  • Can take multiple years to migrate the entire system
  • Requires more legacy DCS expertise for delivery engineering team

Full migration benefits:

  • Complete system is available in just weeks instead of years
  • Optimization offers immediate results and access to more data for better decision making
  • Requires less legacy DCS expertise for delivery engineering team

Full migration drawbacks

  • Requires extensive shutdown
  • Usually funded through a capital expense budget
  • Higher risk

What's right for you will depend on the goals you want to achieve, and how fast you want to see results.

No matter your situation, or your timeline, one thing is clear: in my experience, the time to “fix” something is before it's broken.

Mike Vernak
Posted October 3, 2016 By Mike Vernak, Product Manager, DCS Migrations, Rockwell Automation
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