Feedback: Criteria for PLC vs. DCS evaluation
I read your article about the Eli Lilly engineer’s (Mike Alward) comparison of PLC versus DCS. [ Control Engineering Weekly News email newsletter, Oct. 31, 2006; “ Automation Fair: Pharma engineer rates PLC system over DCS .”]
What were the 19 criteria used to compare? This is so I can understand the viewpoint of giving a 77-73 lead to the PLC. We do run into the comparison once in awhile, and, yes, it [the DCS advantage] does seem to disappear, as PLC functionality gets closer to the DCS. Thank you.
—James Pfeifer, R.E.T., F.S.E, senior control systems specialist, IMV Projects , Calgary, Alberta, Canada
PLC vs. DCS criteria are…
I appreciate your feedback on the PLC versus DCS debate. For those just picking up the discussion, the article, linked above, compares a control system based on programmable logic controllers and distributed control systems. While I included some criteria provided by Mike Alward, lead system architect at Eli Lilly (Indianapolis, IN), I should have figured readers would want them all.
Here are the 19 criteria Alward mentioned:
Control execution speed
Control templates provided
Control templates, ability to create
Cost for implemented system
Global tag, parameter accessibility
HMI development / integration
Integrated hardware solution
Integrated software solution
Integration of non-vendor provided components and applications
OEM equipment, ease of integration with
Programming language capabilities
Redundancy, fault tolerance
System integrators, availability of effective
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