If you work for a machine or robot builder OEM, or if you're a manufacturer with machines and/or robots in your facility, then the subject of automation system obsolescence will arise sooner or later. When it does, you have three options.
One is to rip and replace the entire existing automation system with a new one, an option covered in detail in our June 2013 Control Design cover story "Old Machine, New Life" and touched on in this article. This is the highest-cost option with the most downtime, but the result is a new system that can run for many years.
The second option is to keep the old automation system up and running for as long as possible through a combination of wit, grit and spit. This is the lowest-cost option, but can't be sustained forever, as sooner or later it will become necessary to either rip and replace or retrofit.
The third option is to retrofit part of the automation system with new components, while keeping other parts in place.
In almost all cases, a retrofit will require less downtime than a rip and replace because the scope of work is greatly reduced. It's also better than a simple "keep running" solution because it replaces the parts of the automation system that cause the most problems.
Also Read: The Pros and Cons of Embedded HMIs For Machine Builders
In many cases, the base machine is fine, but the control system needs upgrading. Georg Transformer in Germany had that problem with a 1981 lamination shear that it builds for transformer manufacturers. The machine had an ancient 486 PC for the controller. Georg found an upgrade path that let the original I/O work with a new controller in an almost plug-and-play project. (See the sidebar, "Save the Old I/O," p. 26 for more on this retrofit.)
Another reason to retrofit arises when support has disappeared for the original control system. Michael Lindley, vice president at Concept Systems, a system integrator in Albany, Oregon, first got involved with an aerospace company 12 years ago, when the company that installed and supported a rivet inspection control system went out of business. "We first duplicated the controls, supported them through the life of the system, then re-programmed the machine with all new hardware, but with the identical look and feel," Lindley explains.
The inspection system checks each rivet just before it's inserted into the wing skin and crushed to make sure it's the right rivet, is not upside down and is oriented precisely vertically. It communicates directly with the CNC system, and uses a pair of orthogonal cameras (cameras oriented so that one sees a front view and the other a side view) with custom backlights.
"We installed the first system with Visual Basic 6 and Windows XP," Lindley says. "The new system uses Visual Studio 2012 and Windows 7/64. We increased the resolution with the third-generation system, although the accuracy of the previous system was adequate."
Upgrading because of Windows operating system problems is a major reason for retrofits. Support for Windows XP ended in April 2014, affecting thousands of PC installations.
One force driving the switch to Windows 7 is the old age of the PCs that run Windows 2000, Windows XP and older operating systems. We often hear that when the old PC dies and must be replaced, users with control and HMI systems that are working OK are forced to make major changes. This raises another problem, Tom Edwards, Opto 22 engineer, observes: "The mandatory shift to Windows 7 and Windows 8 on all of the available newer PCs makes a change in control and HMI software a necessity, as very few of the fundamental I/O functions remain the same or are upgradeable to Windows 7 or Windows 8."
Picking on PLCs
Brains Brewery in Cardiff, Wales, was developing an increasing variety of beers, so it wanted to upgrade its yeast-handling control system to accommodate the new mixes. "The main aim of the project was to upgrade two Allen-Bradley PLC 2 controllers, which were 27 years old," says Mike Cooper of IAC Engineering (www.iaceng.com), a system integrator in Cross Hands, U.K. "Limited downtime was available—only three days—so the six old 1771 remote I/O racks were retained, but the obsolete controllers were replaced by a CompactLogix PLC."