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This week at Rockwell Automation's Process Solutions User Group (PSUG) meeting in Philadelphia, end users shared stories of their successful risk-management decision-making in the face of system obsolescence, and Rockwell Automation presenters shared the depth and breadth of tools and services they've developed to help manage that inevitable time when good automation systems begin to go bad.
Many of the control systems in current use were installed in the 1980s—or before—and are well past their envisioned services lives, according to Lonnie Morris, global product manager, Rockwell Automation, in his presentation to PSUG attendees. "The number of products becoming obsolete is huge," he acknowledged. "Obsolescence risk is a risk that you take—knowingly or unknowingly—by using products that no longer are supported or serviceable," Morris said.
A number of risk factors begin to escalate as automation products from any manufacturer move from the active production stage through what Rockwell Automation calls their "silver" stage (12-24 months of remaining production) to discontinued status, when repairs may be made, but replacement parts are not being manufactured. When a product has been discontinued, repair costs can exceed original hardware costs, and it gets harder to find subject-matter experts familiar with these systems, Morris explained. And it isn't just the advance of technology making products obsolete. Component supply chains are especially fragile, as diminishing demand, supplier mergers and failures, as well as regulatory requirements such RoHS take a toll on component availability.
If your plant is running on obsolete automation systems—parts-sourcing on eBay is one likely indication—it just might be time to undertake a more formal assessment of the risk that these systems pose. Morris recommends a three-phase process in which you first assess what systems you have; second, quantify and prioritize risks to the operation; and third, develop an appropriate mitigation/migration plan.
Once the operational risks to continuing operation have been properly identified, it's time to make a plan for moving forward. Rockwell Automation can help develop a mitigation plan designed to support elements deemed sufficiently "non-critical" through preventive maintenance and access to technical support and spares replacement and/or repair of legacy systems. "The goal is to develop an overall plan that will buy you time to implement your migration strategy," Morris said.
Even the decision to eliminate obsolescence risk by migrating off older technology isn't totally risk-free. Considerations then include such factors as necessary downtime, new code development, training, network compatibility, field wiring and disposal of legacy products. Among Rockwell Automation's strategies designed to help manage even these risks are "drop-in" replacement systems and tools for migrating from a range of competitive control systems. "Our phased, StepForward process includes a broad range of conversion enablers," Morris said. "It allows you to step forward without a massive capital outlay."
"Implementing a single control platform across all plant-floor applications provides our customers with a number of advantages, including reduced spare-parts requirements, more synchronized processes, and lower maintenance and training costs," said Mike Vernak, DCS migrations program manager, Rockwell Automation. "It also improves plant-wide integration by enabling the seamless transfer of real-time data from disparate control systems for improved decision making and increased manufacturing flexibility."
New migration tools released by Rockwell Automation in the past several months include:
I/O scanners shadow the existing system and pull data during run-time into the new system's Allen-Bradley ControlLogix controller. This data is used to simulate and test the system to mitigate risk during the conversion. In addition, Rockwell Automation has developed custom field termination unit cable designs that allow the removal of legacy I/O without the need to remove field wires, significantly reducing installation costs and risks associated with I/O replacement. On one end, the custom cables plug directly into the legacy field termination unit, and on the other end, into the ControlLogix I/O module.
Rockwell Automation also leverages database and configuration utilities that convert existing control strategies into information that the PlantPAx system can understand, rather than having to rewrite them from scratch. This helps reduce risk, engineering time and overall project time.
At Ripon Cogen's 50-MW cogeneration plant in Ripon, Calif., an aging balance of plant (BOP) control system had "been on its last legs for a number of years," said Jim Groff, plant manager. Elements of the old system, including the historian, had malfunctioned and proved unfixable. "But the deciding factor was when the new CEO of our company visited and saw what we were working with. It took him 30 minutes to decide ‘We're putting a new control system in,''" Groff said.
With project justification thus settled, the company engaged Maverick Technologies and its "DCS Next" methodology, ultimately settling on Rockwell Automation's PlantPAx platform for a full control system retrofit. Among the key system attributes of the new DCS were state-of-the-art hardware, open control networks, nearby availability of hardware parts and I/O capable of handling smart HART transmitter communications, said John Boyd, technology leader, Maverick Technologies. From a software perspective, Microsoft server and desktop software, a world-class historian and ready availability of local systems integration capabilities were must-haves. And Maverick worked with Rockwell Automation to develop and deploy custom interface cables that would facilitate the system migration without disturbing existing field terminations—plus accommodate the desire to access HART transmitter data.
Work began on the project in February 2012, and cut-over to the new system was actually underway during the PSUG event. Beyond the obvious benefits of a workable, maintainable system, Groff looks forward to reaping the benefits of newly automated start-up sequences, advanced reporting and fewer spurious trips that had plagued the older system—and torpedoed overall plant productivity. "Now if there's a trip, we'll know there's really something wrong," Groff said.