What's a DCS?

Somebody wrote to the A-List at control.com a while back, and claimed that while XYZ and ABC were DCS systems, two other companies' systems, in his not-so-humble opinion, didn't qualify. Last year, in a discussion with Emerson's Chief Strategic Officer, Peter Zornio, we came up with the following definition of a Distributed Control System: "A DCS is a set of proprietary field controllers connected to field devices via analog or digital field level networks and connected to a central control function via open networks such as Ethernet. The Central Control function consists of COTS (commercial off the shelf) computers running a proprietary integrated software suite." That pretty much allows any field controllers with an integrated set of software running them into the definition, don't you think? Last week, in a discussion with Rockwell's Rick Dolezal, the subject came up again. Rick noted that nobody sells DCS systems anymore, and offered this list as evidence: Who sells a DCS? No one, apparently...From each of their web sites: Foxboro (InFusion) - Enterprise Control System Honeywell (Experion) - Process Knowledge System Emerson (Delta-V) - Digital Automation System ABB (800xA) - Extended Automation System Siemens (PCS 7) - Process Control System Yokogawa (CENTUM CS) - Integrated Production Control System NovaTech (D/3) - Process Automation System Rockwell Automation - Integrated Architecture for Process So, if nobody is making DCS systems, what are all those end users buying?

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  • I don't use the term DCS any more, with the new systems using control in the field there isn't DCS any more. Not in the old sense of TDC3000 and RS3, etc. I use the term 'control system'. Peter's definition of a DCS is just wrong, it excludes the ORIGINAL DCSs of the TDC2000, TDC3000, RS3, etc. era. They didn't have 'open networks such as Ethernet.' or 'COTS (commercial off the shelf) computers running a proprietary integrated software suite.' Peter is describing a modern 'control system' (CS) not a DCS. I remember asking for these features from the DCS vendors, seemed like a good idea at the time. Now that we've lived with them for a few years, I'm not so sure it was a good idea. We didn't have to worry about virus, OS updates or all kinds of headaches that the COTS systems have. My 2 cents for what it's worth... Dave My first DCS work was in 1980 on a TDC2000.

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  • My mistake...Peter and I were talking about a "modern" DCS, and how the definition has changed, exactly as you said....Peter was not wrong, I didn't explain the discussion correctly.

    Walt

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