Users Weigh Risks in Migration Decision

Tools Help Minimize Migration Risk

"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:

• Database conversion, cabling solution and I/O scanner for migrating a Siemens Moore APACS system;
• Cabling solution and improved database-conversion tool for migrating an Invensys Foxboro I/A system;
• I/O scanner for Allen-Bradley SMART I/O for migrating an Emerson Fisher Provox system; and,
• Universal Control Network interface for migrating a Honeywell TDC3000 system.

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.

From Legacy DCS to PlantPAx

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.