How to keep those legacy systems running

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Keywords: legacy systems, legacy software, motion control, servo motors, stepper motors, motion control software, Hydraulics, Pneumatics, electro-Mechanical, factory automation systems, industrial automation, process automation, automation engineering and control systems

How do you keep an old machine control system running? Senior Tech Editor Rich Merritt reports on lessons machine builders have learned about how to maintain legacy systems for you and your customers.

By Rich Merritt, Senior Technical Editor

Our recent survey about control platforms (It’s All About Platform -- Feb. ‘05, p28) revealed that 68% of you have been using the same platform for more than five years. How do you keep some of those old systems running? How do you continue to keep building machine controls based on older technology? After all, vendors announce new products every day, technology marches on, and legacy system parts can become scarce real fast.

The answer to both questions is pretty clear. You can keep those old timers humming right along by understanding what the automation vendors in our business are doing to provide product support, service and parts for systems they had a hand in all those years ago.
 
It Lives
If you use an Allen-Bradley PLC-5--a system that has been around for 20 years--as your control platform, you are probably a happy machine builder because you can buy a new PLC-5 whenever you need one. Rockwell Automation still builds them, and you don’t have to hunt for parts, because the company continues to support the controller with parts and service.

JVH Engineering, a machine builder in Grandville, Mich., has used PLC-5s for 18 years in its injection molding machines. They continue to support their customer’s PLC-5s (See Figure 1), and they still use them in their new systems. “We designed our new system around an SLC 500, a PLC-5, ControlLogix and CompactLogix platforms, so that customers that wish to maintain legacy systems are able to do so,” says Rodney Rotman, vice president of JVH.

This kind of support looks to be the case for many of the automation vendors. In fact, the bigger they are, the more it appears that they try to help machine builders who are running legacy control systems. It is easier to retain existing customers than it is to land new ones. The automation vendors know this too.

However, a little perspective is in order, as noted by Steve Connell, manager of systems engineering at machine builder Glasstech Inc., Perrysburg, Ohio. “Yes, it is easier to keep an existing customer than to land new ones,” he admits. “However, this is a double-edged sword. When competitors are able to undercut you because they do not offer this type of support, and the customers are looking for their short-term ROI, it becomes difficult to get people to purchase a machine to run for the next 20-25 years. Most people making these purchasing decisions will be retired before the machine is.”

Rick Caldwell, president of SCADAware, a system integrator and machine builder in Bloomington, Ill., has been building machines for 20 years. He says sometimes customers just throw good money after bad. “If the equipment has enough age, we advise our customers to upgrade to newer controls whenever something breaks,” he says. “I’ve seen customers baby old machines for way too long. There’s not much sense in buying older controls or I/O cards when newer devices cost about the same. But I always ask how long they intend to keep using the machine. If they only expect to keep it going for another two years or less, then we recommend fixing the old controls.”

In some cases, a total upgrade might be necessary, as Caldwell points out, and both machine OEM and customer can make the financial case for ripping out the old and putting in the new system. As we point out in Good Migrations (May ‘04, p24), it is a good way to drag a legacy system into the 21st Century. We will not go back over that ground this time around, but, as you’ll see, sometimes upgrading a part or a controller here and there can be a necessity, a great improvement, or both.

Look for Long-Term Support
Another obvious problem involves continuing to build new control systems based on old technology. Systems, parts and components that were readily available five or 10 years ago might be getting scarce today. What you need (and what your customers need) is a good, reliable source of parts over the long term.

If you are using a control system from an established vendor, this might not be a problem. “Customers typically receive two years notification of obsolescence and a seven year minimum support plan including spare parts, inventory, returns and repairs,” says Mike Miclot, marketing manager at Rockwell Automation. “This allows them time to do last-time buys and plan their migration strategy.”

Schneider Electric markets Modicon, Telemecanique and Square D PLCs, and supports all the products it sells, plus the legacy systems. “Once a product ends commercialization, we do our best to deliver support and parts, including repair and replacement services, for as long as possible,” says Brian Owens, marketing manager at Schneider. “For PLC products, typically that’s 10 years.”

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