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Here is a reference: Practical SCADA for Industry, Bailey, David and Wright, Edwin, Newnes (publisher), 2003. Page 12 “A SCADA systems means a system consisting of a number of remote terminal units (or RTUs) collecting field data connected back to a master station via a communications system. The master station displays the acquired data and also allows the operator to perform remote control tasks.” “SCADA has the connotation of remote or distant operation.”

Page 15 “In a DCS, the data acquisition and control functions are performed by a number of distributed microprocessor-based units situated near to the devices being controlled or the instrument from which data is being gathered. DCS systems have evolved into systems providing very sophisticated … control capability.” “The data highway is normally capable of fairly high speeds…”

Forgot to add that DCSs are primarily found in manufacturing environments and the various computing modules are geographically close to each other. Examples of DCS control applications include refineries, chemical plants, power plants, (but some power plants use SCADA software for control) pulp and paper plants and food processing. DCSs also operate in one of two ways - discrete or continuous. Discrete refers to batch jobs where there is a recipe or blend that has a start and distinct stop. Lubricant plants use discrete DCS controls as well as food industry (make 5000 cans of tomato sauce today and 5000 cans of pasta sauce tomorrow). Continuous process control is where once it is started you let it run for as long as you can. Refineries, chemical plants and power plants are examples. In the DCS, the only difference between discrete and continuous is the control logic.

--Jay abshier (talk) 20:08, 28 July 2009 (UTC)


The distinction between SCADA and DCS is somewhat accurate but incomplete. Yes, SCADA systems coordinate control devices such as PLCs and RTUs or specialized primary control devices - but in many ways so do DCSs. SCADA systems are also usually found in control applications that are geographically distributed. Examples include control of pipelines, oil producing fields and in power industry the control (coordination) of distribution and transmission grids. DCS are distributed in that the functions are distributed to differing compute modules. The HMI is one module, the Engineering Workstation is another, Historians are separate modules, the various Gateways are separete computing modules, usually using OPC, to talk to the primary control devices, which might be PLCs, RTUs or specialized devices for turbines, pumps, etc. My background: Spent 20 years at Texaco, 11 supporting, developing and designing control software for Honeywell DCSs, after Texaco spent 4 years consulting mostly in US on securing SCADAs used to control power grid and controllers in substations. Recently finished designing security for Chevron's standardized process control (refinery) infrastructure and am now working on technical architecture for business level interfaces. Jay--Jay abshier (talk) 20:00, 28 July 2009 (UTC)

No more adverts[edit]

Removed all advertisements in the SCADA Security Issues Section. Take a look, let me know what you thing.--StickyWidget (talk) 01:48, 17 February 2009 (UTC)...

[1]Something completely different: I noticed that in fact all external links point to commercial websites and can be seen as advertisements or commercial links. It is safe to assume this is not allowed or should not be allowed. Ramkay's link ( further down on this page ) is the only one I can see as useful for this article --HaPi 13:29, 15 April 2007 (UTC)
Hi HaPi, Do you think we should add this link in the external links? --Ramkay
Nope. I don't think the link should be added. (Requestion 06:12, 30 April 2007 (UTC))
See [1] and [2] for reasons why adding the link is a bad idea. (Requestion 21:24, 30 April 2007 (UTC))

PLC vs RTU?[edit]

Correct Gadz, I noticed it and I didn't change it. Probably the differences between PLCs and RTUs are becoming less clear in time? I think Communications between centres ("SCADA" or "DCS") becoming faster and simpler, protocols like ICCP, make the difference between scada or dcs less important and -indeed- the whole thing could as well be called Control Systems. --HaPi 20:51, 10 July 2006 (UTC)

oh, by the way, I removed all links that can easily be found by googling. I humbly apologize if by doing so I hurt someone's business, if I removed a link from a sponsor of this site I'll put it back personally. --HaPi 20:51, 10 July 2006 (UTC)

Merged Definitions[edit]

Also , the article seems to merge the definitions of SCADA and DCS. Traditionally SCADA consisted of RTUs and Master Stations over Geographically Distributed areas. It was defined as a Supervisory Control And Data Aquisition system which included both RTUs, Master Stations and the communications networks in between. These days a few Marketing gurus from companies like Wonderware and Citect have branded the HMI's as SCADA.

PLCs were more associated with DCS systems and were closed loop systems. Feedback from field IO was expected to be immediate where SCADA was traditionally expected to log field changes and send them back in bursts (though not always the case).

Today Control Systems combine the technologies from SCADA systems, DCS systems and internet technologies to form all sorts of hybrid solutions that have more do to with engineering control system solutions and less about the technical definitions that gave birth to these technologies.

In essence SCADA ain't SCADA anymore. It would be better to call them all Control Systems.



Modbus is not a SCADA product, it is a communication protocol like Proflibus. Wonderware is a better example of a SCADA product

  (Gary84 said -- Wonderware is more of an HMI product)
I think Gadz and Gary84 are missing a few details: SCADA is a design philosophy, not a product. You don't go to a store and buy a piece of SCADA. Toward that end, ModbusRTU is a protocol. It can be part of a SCADA system if it is used that way. The whole thrust of a SCADA sytem is that one is supposed to use Supervisory commands and data. Thus, control loops are not meant to be closed through a SCADA system. They're meant to go no further than the RTU. Upon loss of communications, the RTU is intended to continue working with its control loops and perhaps to execute some sort of local control strategy to keep product moving or perhaps to safely shut down. Also, I agree with Gary84, Wonderware is an HMI, an element of a SCADA system, not a "SCADA product". Scadateer (talk) 17:24, 9 May 2008 (UTC)

*Nice* work[edit]

I've just inlinked this page from NOC; please let me say that this article, while on a topic that's a touch esoteric, is *very* well written. In today's environment, I'm not sure you'd wanna feature it (no sense giving the Bad Guys<tm> any extra ideas, but still... Nice job, all. --Baylink 07:02, 30 Jan 2005 (UTC)

Possible copyright infringement?[edit]

Look at this page:

Please apply the {{copyright}} template to the article if a copyright may be infringed. -- Fingers-of-Pyrex 22:31, 2005 May 15 (UTC)

There's also parts copied straight out of The rules are "Wikipedia content can be copied, modified, and redistributed so long as the new version grants the same freedoms to others and acknowledges the authors of the Wikipedia article used (a direct link back to the article satisfies our author credit requirement)." As far as I know this article doesn't give any credit back to the author. I suggest putting this article up for speedy deletion. Rejnal 03:33, 31 January 2006 (UTC)

Copyvio? [3]. John Vandenberg 13:40, 23 June 2007 (UTC)

Glib ?[edit]

In Manufacturing SCADA usage is driven by cost saving achieved through automation. Most SCADA packages can deal with many different controllers so perhaps just quote Control Industrial Processes such as Civil Engineering; Trafic Lights/Mass Transit; Process Control (Automation of Manufacturing)etc. Again in Manufacturing SCADA systems are used to bring together several autononimous controllers (perhaps from different manufacturers)and present the process information to operators in a concise standard manner; independantly of the controllers own interface. Use of TCP/IP as a communication link is on par with the use of RS232, RS485 links or optic fibre. Also note that OPC is fast making SCADA front ends easier to implement across open systems; again the underlying communication architecture is irrelevant.

Clarity of definition[edit]

I came to this page because I've never heard of SCADA before. I'd like to finish reading the first couple sections and have some idea of what is SCADA and what isn't SCADA. All computers are control systems. All computers do communications. All computers have inputs and outputs. What special and unique features are required to earn the SCADA moniker?

Is it the fact a set of industrial and/or scientific tools are involved? Could email software be considerd SCADA? Could an SNMP controller? What about a home network using X10 devices?

Ebyrob 01:41, 2 March 2006 (UTC)

I agree. Reading this, I felt like I was reading about Ice: "Ice is cold. Ice floats. Ice has fourteen phases:... Ice can be an insulator, in the following ways..." and the article never got around to mentioning that ice was the solid phases of water. The article says a very great deal about SCADA, but not much about the definition of SCADA. --TreyHarris 12:42, 22 March 2006 (UTC)
I've rewritten the opening paragraph. I hope this fixes the problems you have understanding what a real SCADA system is. Scadateer (talk) 17:24, 9 May 2008 (UTC)

External links[edit]

All those links make the article look like an advert. Are they all really necessary? Kevin 07:31, 16 May 2006 (UTC)

I agree, and these links are not necessary. I'll take them out in a few days, unless someone comes up with a good reaso to let them be. --HaPi 12:15, 12 June 2006 (UTC)

I think this is a very good discussion of SCADA though as usual tending to blur SCADA and DCS - may be what it requires is a 'simple' explanation at the top - I came to this page after checking the DCS page and adding what I hope may be a clarifying difference between SCADA/PLC and DCS - and yes I work in a job where I have to deal with both SCADA/PLC solutions and DCS solutions.

DCS implies a top down factory wide solution to a process. The process is whatever the factory as a whole makes (ok in refineries there will be autonominous units that equate in practice to seperate factories). Alarms and reports are generated by the DCS

SCADA/PLC implies a bottom up solution - frequently ending up in an accidental fatory wide solution. Alarms are generated by the individual PLC's. Reports are generated by querrying the PLC's

Petedtm 21:05, 9 August 2006 (UTC)

This link is a knowledge base on Scada . I am sure some may find it useful. If anyone else agrees then this link can be added to the external links? ramkay

Hello Ramkay. You asked this same link question up above and the answer is no. (Requestion 21:24, 30 April 2007 (UTC))
Looks like advertising is slowly creeping back in... AWoodland (talk) 07:18, 14 January 2009 (UTC)

Future trends in SCADA[edit]

Is this section really appropriate for an encylopedia? It seems like someone's predictions and opinions and not what Wikipedia is about. Also, I don't agree with it but lets not argue opinions here. -Crunchy Numbers 16:59, 20 September 2006 (UTC)

I agree. I feel this section ought to be deleted. One doesn't read an encyclopedia for future prognostications. Scadateer (talk) 16:58, 9 May 2008 (UTC)

North America?[edit]

What North America means here ? Mexico, USA and Canada ? Or just Canada and USA? Or just USA?

Systems concepts - Vendor list[edit]

The Systems concepts section has a list of vendors that I cleaned up. (Disclaimer: I have a relationship with GE Fanuc and I want to make sure I did it in a NPOV way.)

I undid the addition of LABTEKNIX to the list of SCADA suppliers. What is it? Google, Yahoo, and Microsoft Live searches find no references.

I alphabetized the list, added Wikipedia links where appropriate, and moved SUPCON and Telvent from PLC hardware/software to HMI software list.

The lists seem to be listing companies and not products. Given that, I have a couple of questions:

  • DirectLOGIC seems to be the product rather than the company. Is Automation Direct the company?
  • Adroit seems to be the product rather than the company. Is CIMNET the company or is it now fully part of Wonderware?
  • Citect is now part of Schneider Electric. Is CitectSCADA still sold by Citect as a company or is it just sold by Schneider?

Note that it might be more appropriate (less controversial) just to remove the list of vendors.

--Ishi Gustaedr 16:17, 20 August 2007 (UTC)

SCADA are not control systems[edit]

SCADA systems are not control systems, but the article hints as such. The word "control" in SCADA is qualified by "supervisory". I just hope some expert rewrites this page. Hi pedler 09:35, 28 September 2007 (UTC)hi_pedler

Not necessarily. My company represents a SCADA system that can do complete control using internal logic to eliminate the need for PLC's. Local RTU's can do real time control at the site as well as offer the near real time supervisory control from a remote location. They can send and receive digital and analog signals based on programmed logic to control most systems attached to it. Utilitysupplies 21:02, 28 September 2007 (UTC)
The definition of SCADA is getting very muddled due to an excessive number of mainstream articles referring to all industrial control systems as SCADA. However, the generally accepted definition of SCADA is a system which uses predominantly open loop control (in other words, a control system with a human in the middle) over slow speed links. Closed loop controls are often found in a DCS. The closed loop controls in a DCS are generally found on a campus, where communications via a LAN are common. The open loop controls in a SCADA system generally have very slow reaction times (typically measured in fractions of an hour or more). That is not to say that DCS will never have open loop control or a SCADA system shouldn't have closed loop control. It merely indicates an overall design philosophy. --Scadateer (talk) 22:50, 27 April 2008 (UTC)

A scada system does things in real time. It is not slow by any stretch. Unless you count the time an operator does nothing while an alarm is sounding. I have designed build and installed SCADA systems that use fiber optic and Ethernet communications. Real time information coming into a PCL from equipment is instantaneous. I will admit that back in the late 70's and early 80's thing where not very fast but those days are way way behind us now. Scada systems now can easily be measured in milliseconds or faster. Maybe I missed something this author was trying to get across. But a scada system is very fast in every aspect of it. (( Madhatter)) 11-16-2011 15:16:02 — Preceding unsigned comment added by (talk) 21:16, 16 November 2011 (UTC)

Europe versus The World[edit]

It is not immediately obvious from the article where the statement "In Europe, SCADA refers to a large-scale, distributed measurement and control system, while in the rest of the world SCADA may describe systems of any size or geographical distribution" comes from. I have read about the differences in protocols (IEC vs. DNP3) between different regions, but this statement seems to refer to the scale and terminology used in different places. I don't know of any references that support this, and every time I try to search around about it, it all comes back to (essentially) "the Wikipedia entry says so" .

If anyone (perhaps the contributor who added that statement) knows, a reference would be nice, or some explanation. —Preceding unsigned comment added by (talk) 02:15, 18 February 2008 (UTC)

I fixed the assertion. Most of the differences between Europe and North America are a matter of which standards are in use, not conceptual issues such as what SCADA means. Scadateer (talk) 16:56, 9 May 2008 (UTC)

SCADA as a hosted service[edit]

In the Trends in SCADA there is a paragraph on SCADA as a hosted service. Can we get a good reference that identifies this as trend? I know some vendors have already been doing this for a long time through their services departments rather offering it as a product. I realize the content may have initially appeared as an advert, but I think there's some worth in the paragraph. I tried to add some balancing information, but it's not well sourced. --Ishi Gustaedr (talk) 13:31, 30 May 2008 (UTC)

I don't think speculation of what the future may bring has much relevance in an article such as this. Besides, hosting a SCADA service doesn't seem like a terribly bright idea to me. The latency, security and liability problems for a service provider aren't trivial. If this is a trend of the future, I haven't heard of many sales. I propose that the text concerning this be deleted on the grounds that it is speculative, unusual, and unproven as a business model. Scadateer (talk) 23:36, 17 July 2008 (UTC)

SCADA v DCS[edit]

Sorry the reference to SCADA and 'an HMI' destroys the argument that they are the same thing. A DCS is based on top down methodology with single point of engineering as a given; therefore the HMI is not a separate entity; nor is the database etc.

The biggest difference lies in the design philosophy : top down or bottom up. DCS remain top down seeing the control system as an integrated whole; SCADA systems remain a bottom up mix of sub-systems generating a totality that superficially appears (if properly engineered) indistinguishable from a DCS

Remove Citation-Needed[edit]

In the discussion on how security threats can be mitigated, the following sentence has been tagged as needing a citation:

"Additionally, application whitelisting solutions are being implemented because of their ability to prevent malware and unauthorized application changes without the performance impacts of traditional antivirus scans [citation needed]."

If the missing citation refers to the claim that whitelists are being implemented _because_ they provide security without the performance hit of an antivirus scan, then I believe the tag is unduly applied. It is a fact of the architecture of whitelisting that it does not require scanning. It is also a fact of operation that a scan imposes a performance cost. To implement whitelisting is therefore a simple optimization based on the facts at hand, not an opinion that requires an authoritative source.

I recommend that the citation-needed tag be removed.

Dave.marney (talk) 12:42, 31 July 2010 (UTC)

Platform Independent SCADA[edit]

Does anybody know about the SCADA system which works on Windows and Linux? We are interested in Modbus protocl... —Preceding unsigned comment added by (talk) 10:47, 30 October 2010 (UTC)

I was bold[edit]

I made a number of revisions this evening. Most were reference related, or grammar, proper formatting of bare svg images, etc. I tried to clean up the designations for "citation needed". And of course, I tried to change the point of view from someone writing this in 2006 or so, and update it to May 2012. I looked up the correct ISBN's from Springer etc for the 1st ever "hardware malware" in Australia, and tried to convert bare URL's into bona fide references. I didn't want to change any of the companies that were linked to, as it appeared you all had been pretty thorough about weeding out gratuitous advertising links.

My concern was that in clarifyng wherever it said "citation needed", that I didn't link directly to something that was unnecessarily umm detailed for Wikipedia. I truly wanted to remove that section about ICA and the WG4 "eventually" having standards established by 2011, as that was so very out of date.

Finally, I was uneasy about removing the section about ICIS, as it had been there so long. However, when I searched the ICA website, it led me to Excida LLC website, and I couldn't determine if that certification was truly associated in an exclusive and unique way with ICA WG4 or was just another certification program and not necessarily for SCADA or industrial control systems (even though it might have been back in 2009). I checked websites etc, remained uncertain, so replaced that part with the quote from InHit magazine via ICA.

Regarding white listing of safe apps etc, I did find likely confirmation, but it was within draft docs of the WG4, version 3, part 4, which I didn't know was a stable release or on the living end of a living document. It was last updated in Sept 2011. Furthermore, it would have been careless to link to the PDF from WP given the nature of the document.

If there's anything you didn't like, or want me to change back, I will do so. I would like it if Scadateer or ANYONE who is still actively watching this page review my changes.. just in case. --FeralOink (talk) 15:30, 2 May 2012 (UTC)

SCADA over internet[edit]

I removed the following paragraph. It is misleading because it suggests that connecting SCADA systems to the Internet can be secure if cellular networks are used. Cellular data is encrypted, but this only over the cellular access network i.e. it is only encrypted between the end user cellular equipment and the service provider.

Although some believe it is good security engineering practice to avoid connecting SCADA systems to the Internet so the attack surface is reduced, many industries, such as wastewater collection and water distribution, have used existing cellular networks to monitor their infrastructure along with internet portals for end-user data delivery and modification. Cellular network data is encrypted before transmission over the Internet. — Preceding unsigned comment added by XtraChewy0 (talkcontribs) 12:17, 24 October 2012 (UTC)


I worked in SCADA years ago and I always heard it pronounced SCæDʌ (first A long, second A, like "uh"). I'm hearing the term used more and more in the press, but often with different pronunciations. There are discussions on the net about this. Is there an authority on such matters that we could refer to here? Even if there is controversy, perhaps we should have a section that mentions the controversy and who pronounces it in the different ways. JordanHenderson (talk) 13:39, 19 October 2013 (UTC)

Fourth Generation - Internet of Things[edit]

The last sentence of this paragraph, "One such example of this technology is an innovative approach to rainwater harvesting through the implementation of real time controls (RTC).", provides no explanation for how it was implemented, or what made it possible that wasn't present in past generations. Perhaps a link to an article detailing it's use could be added, or the sentence could be removed. (talk) 21:20, 2 December 2014 (UTC)

Source for "Fourth Generation"[edit]

I haven't found any bibliography referring to SCADA using IoT as "fourth generation". Was this made up in this article? NCS' PDF only lists the first 3 generations (it's from 2004), I understand the fourth one would be logical but there should be some reference to support that. Tharos (talk) 19:41, 1 July 2015 (UTC)

Broken reference link (NCS)[edit]

The link for ncs appears to be broken (actually I can't reach at all). I think this is the same file but I'm not sure: Tharos (talk) 19:41, 1 July 2015 (UTC)

Ok, I changed it Tharos (talk) 14:58, 30 July 2015 (UTC)

External links modified[edit]

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Cleanup - 2016[edit]

In response to the cleanup template, I have now removed repetition and deviation, and formatted the narrative logically. Random statements have been removed, multiple technical terms have been rationalised to those actually used, and the concept of a control hierarchy and the similarities and distinction from DCS explained. Links added. SCADA added to manufacturing template. Dougsim (talk)

  1. ^ mr vinay kumar chandana