Talk:Distributed control system

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Electronic digital based DCS goes back to circa 1974 with Honeywell (and others) launching digital DCS eg TDC200. BBC (Brown Boveri et Cie now part of ABB) also had a digital DCS. By the 1990's most large industrial plants had replaced the majority of pneumatic and hydraulic control systems. In the early 2000's most Industrial DCS's were ported to Windows (R) OS platforms after presure from cost cutting and emmbedded IT infrastructure.

Not every distributed control system is part of a manufacturing system. Big ships have them; jet planes have them, etc.

[edit] DCS and SCADA

somwhow i belive that SCADA is the new word and DCS was mostly used until the early 90`s if you take a look at the homepages of different providers, all are calling their system SCADA and somewhere in the text DCS popps up.

the differences are minute and the article should be merged with SCADA

SCADA I usually think of as related to controlling something that's spread out over a wide geographic area, like a power grid. Distributed control I usually think is spread over at most a plant site, and "closes the loop" for process control - SCADA systems to my way of thinking just monitor or alarm, and leave loop control to local elements. Both terms are still in use and I think they don't entirely overlap - I'd object to merging the articles. (You can create a user ID and sign your remarks!) --Wtshymanski 22:17, 30 May 2006 (UTC)

DCS is NOT SCADA anymore than an analogue computer is a digital computer !

DCS = top down design solution to factory automation : hence Distributed control system; as it is integrated at the highest factory wide production level; it includes alarming; recording; control and monitoring complete with an integrated graphical front end (HMI or Human Machine Interface). Minimal number of diferent tools to configure; normally everything runs under a common control system (at computer level) SCADA = Supervisory Control And Data Acquisition - normally displayed using a (third party) Human Machine Interface. In any given plant (factory) there may be several diferent SCADA systems - sometimes from different suppliers. PLC - individual controls - commonly used as stand alone 'skids' that control logical sub-units of plant - frequently now attached to a SCADA front end to give central control. By default this is bottom up design.

DCS engineers frequently deal with factory wide apllications; PLC engineers frequently deal with single machine/unit control.

With the drive to more and more open standards (cf OPC ) DCS suppliers have had to make their previously be-spoke systems more and more open. At the same time the need to integrate at the lower machine level is driving PLC suppliers to offer more and more integrated systems. Resulting in an ever narrowing gap between top end PLC solutions and bottom end DCS.

The main differential therefor is that DCS requires a top down factory/plant wide design with as little interaction with low level control as possible whilest SCADA/PLC continues to be a bottom up desgin more concerned with intimate dealings with 'bits & bytes' level of machine control. Petedtm 20:49, 9 August 2006 (UTC)

SCADA can be and is increasingly a sub-system or process I/O data provider of a DCS system. The DCS system, one performing process monitoring and closed loop control (Set Point - Process Value = Error --> output), indeed will include field instrument inputs as well as SCADA system inputs. Control points may be comprised of but not limited to one type or a combination of field input/ output instrumentation, OPC (OLE for Process Control) points, SCADA points and human input. DCS systems, systems intended to monitor and control processes like petroleum refining, chemical processes and raw material production (paper, metal foil, etc), typically include hardware (controllers, SCADA, PLC or even other DCS systems) to interface with real world devices (pumps, switches, valves, fans, etc). The controllers are compact computers system in their own right but offer limited or no human access without use of a programming computer networked to the controller and acting as a terminal or station. The DCS more often today represents the front end of associated controllers, PLCs or SCADA devices and may be used to modify SCADA, PLC and controller control routines and I/O module assignments.[CDJ, 2215 GMT-5 21NOV2006]