Automation Fair: Pharma engineer rates PLC system over DCS


Baltimore, MD —An Eli Lilly engineer gave a slight advantage to a programmable logic controller (PLC-based) system compared to a distributed control system (DCS) in a presentation made at a recent media event. The PLC versus DCS analysis was part of 'Manufacturing Perspectives,' Rockwell Automation 's educational forum held the day before its Automation Fair , which took place last week. Some 90 journalists, half from outside the United States, including editors from Control Engineering , Control Engineering Asia , Control Engineering China , and Control Engineering Poland , attended the day-long program.

The PLC versus DCS comparison showed 19 criteria and included uncensored advice for Rockwell Automation about additional improvements for its FactoryTalk and Logix systems. Even so, the analysis gave Rockwell's PLC-based system the advantage, 77 points to 73 for the DCS (1-5 points granted for each attribute).

'Two years ago, we chose a traditional DCS solution. We would not reach the same conclusion today,' said Mike Alward, lead system architect at Eli Lilly in Indianapolis, IN. Alward, no PLC stalwart, has 22 years with the pharmaceutical company, including work with systems from Foxboro, Fisher, Intellution, Wonderware, Emerson Delta V, and Aspen. A DCS rates higher, in Alward's opinion, for criteria such as advanced control, global tag and parameter accessibility, integrated hardware, and integrated software.

The PLC system scored higher in areas including scalability, cost, and available system knowledge from original equipment manufacturers and system integrators. Alward praised Rockwell Automation for controller-based alarming, upcoming add-on instruction capability, and new security. He asked the company to improve control module library functionality, make tags more global, add to plug-and-play functions, integrate system diagnostics, and integrate configuration.

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Control Engineering Daily News Desk
Mark T. Hoske , editor in chief