Process manufacturing plants have a tendency to keep automation systems and associated networks up and running for decades. Some estimates suggest that easily half of the automation systems controlling North American plants have parts that are at least 20 years old, and 30-year-old systems are not rare.

Those systems do not look like they did when they were initially installed, however. Hard-disk drives, monitors and keyboards that receive constant use simply do not survive over decades, and such old equipment is not available anymore. If you ask your local computer store for an IBM XT motherboard and 20 MB hard drive, you will get some puzzled looks. So, unless your automation systems are brand new, they are likely multigenerational due to obsolescence and devices wearing out.

In some cases, old subsystems and components may be replaced to allow for the higher functionality of newer equipment such as with the human machine interface (HMI) subsystem. Making that kind of upgrade will probably include adding new PCs with operating systems capable of supporting functionality that was not available when the original HMI was installed.

Getting an automation system that includes multigenerational and multivendor components to work together can be a challenge. But, that approach may be the only option when there are not any practical alternatives, and end-users must be prepared to deal with the inherent challenges.

Limping Along Versus Appropriate Upgrades

At some point, an old automation system that has not been upgraded will become a serious threat to production. As printed circuit boards and network devices get older, individual components begin to fail and systems fault more often. These cause unscheduled shutdowns and outages that are especially disruptive when replacement parts are not available.

Some companies specialize in recycling parts for these old systems, and there is always eBay, but supplies tend to get tighter and tighter over time. Individual components — especially the chips — often are long out of production and cannot be replaced. The automation vendor may try to create some sort of functional replacement, but redesigning an old board with new components is expensive, and it will be reflected in the price.

If you know your plant is going to be shut down or go through a major redesign for a specific period of time in the near future, you can limp along with the old system until that date. But that is not an appropriate long-term strategy, and eventually, you will have to go through some type of upgrade or migration.

For purposes of this discussion, an upgrade is defined as adding newer elements but largely sticking with the same automation-system vendor and platform. A migration occurs when you make a major platform change. This typically involves a different vendor but some may choose to stay with the original manufacturer for the new system.

Evaluating an Upgrade Project

Once word gets out that you are considering some type of automation improvements, vendors will come with sales pitches, simulations and lots of promises. An integrator can help sort through the hype and determine what is actually possible, offering unbiased assessments of what products and migration paths actually work.

Cross-platform, multigenerational projects are not easy, and you will need all the help you can get. All vendors can show you good projects, but each one has also had unmentioned disasters. One advantage to consulting with an independent system integrator is the company can speak freely with you about both the successes and failures of a particular vendor.

As you consider launching a project, basic questions that need to be answered include:

• Functionality. What do you expect from your new system at the completion of a successful transition? What new capabilities do you expect to add? Smart I/O? APC? Better enterprise connections?
• Cost. Is your company willing to spend some money to achieve production improvements, or are they seeking the lowest possible cost?
• Operators. What will the operators see? New, modern HMIs with improved alarm management, or the same old thing?
• Schedule.Is there time to plan, or is this an emergency project due to major plant failures? Can the project be timed to accompany a shutdown, or will everything need to be cut over hot?

Some suppliers oversell the capabilities of bolt-on approaches, so an integrator provides the voice of reason. This can mean dumping cold water on some of the sales pitches — a necessary, if often unpleasant, task.

What Should a Project Deliver?

Do not underestimate the value of having equipment that is still being manufactured. You might have forgotten how nice it is to be able to buy spare parts off the shelf. With that in mind, you need to think about what you are buying in the context of a 15-to-20-year lifespan and associated total-cost-of-ownership issues. They include:

• Does the platform have a guaranteed support date?
• Does the vendor have a solid record of supporting its platforms for as long as planned?
• Is this a newer-model automation system, or does the vendor have another system in development that will soon replace the current offering in both support and focus?

New equipment will bring new functionality, and things will not be exactly as they were — nor should they be. Typically, there will be many opportunities for improvements when obsolete components are replaced with newer offerings.

One idea to consider is to bring in operators early in a project to educate them about how a new system can be used to improve operations. This typically includes better graphics, improved techniques for interacting with the HMIs, simpler alarm management and so forth. Explaining how features such as high-performance graphics will improve the control system — supported by findings from the Abnormal Situations Management Consortium — helps show the operators what they can expect to see when the new automation system is up and running.

While often it is OK — for the most part — to keep your basic control strategies, I/O and field devices constant in the new system, you do not want to replicate all of the old functionality in the new automation system. Trying to make a new system behave like an old one ignores many useful improvements, can create a maintenance nightmare and usually requires going to great lengths just to make everything work.

Your system integrator or controls supplier really is not helping you get the best system if the team does not work to convince you to use the built-in capabilities you will be getting with the new automation system. They will present convincing arguments about why each benefit is better for your specific situation, show where the technology is going and explain why deviating from a vendor’s preferred path can be very expensive.

Taking the First Steps

Before you begin to explore available solutions or listen to the first vendor presentation, you need to dig deep in the planning process with questions such as:

• How does the plant run in terms of continuous versus batch, manual versus automatic, and other areas?
• What is the type of production? Long product runs? Short ones? Lots of variations?
• How much money is available for the project?
• What is the condition of the existing automation-system infrastructure?
• Does the scope consider immediate needs and future expectations?
• If you put new controllers in one part of the plant, will those talk to the old controllers?
• Are there supervisory controls that need to talk to both generations of controllers?

Companies frequently get in trouble right out of the gate because they do not evaluate their controllers and networks adequately. New systems invariably create more network traffic and require more processing power, and not all existing systems can handle the extra load.

Consider a typical example of what can happen if a proper upfront evaluation has not been completed. Suppose a plant or process unit wants to install a new HMI to work with existing controllers. However, the plant does not study network traffic and controller loading because everything works fine right now. Unfortunately, they do not realize they are already on the edge of capacity.

Taking a leap of faith that everything will work just like the snazzy simulation shown by the new supplier, they take out all the old equipment and install the new HMIs. The system crashes when they cut over. Or suppose that instead of choosing a vendor that tells them to take out all of the old equipment, the company decides to have both HMI systems work in parallel. Seems like a safe bet — the old one can serve as a temporary backup — but instead, both crash because having both systems requires even more network resources.

There is no substitute for proper planning and testing upfront. A relatively small amount of time and money spent on these tasks can prevent disastrous results down the road.

In conclusion, there is no universal best platform or solution: Each one has its particular strengths for specific types of applications. Likewise, there is no single leading automation system or migration path.

There is much at stake in such projects because the loss of a week’s production, or even a couple days, can easily be worth far more than the cost of the project. (In fact, downtime costs often make a true rip-and-replace approach infeasible due to the economics of lost production, forcing a phased upgrade or migration.)

 Every situation is different, and what works in one facility may not work for you. Success comes from a combination of a deep understanding of the process and control strategy, what kind of shape your controllers and networks are in now and what functionality you need to add. You may need to work with an integrator or other unbiased advisor that can give straight answers for your specific situation. All this needs to be done very early in your planning process so that the projects can be scoped, scheduled and budgeted correctly.