DCS - Distributed Control System????

[sameenkhan]

Hi Guys,

We often use DCS.. we know that DCS is used to control the plant...

My query is related to how Plant Control is distributed in DCS??... and if such question comes how vendors justifies that the system is DCS??

Regards,
Sameen

[ruby_ridge]

The Plant (sub) controllers are distributed throughout the plant and all these distributed controllers are connected for control purposes

[sameenkhan]

Hi Ruby,

Still the explanation does not justifies that how plant control is distributed in DCS...

Regards,
Sameen

[ruby_ridge]

The Plant (sub controllers) each are able to perform a subset of the total DCS function these (sub controllers) can then be Distributed over a large area so the control is Distributed to these (sub controllers)

[sameenkhan]

Hi Ruby,

Well.. I don't agree with the explanation and concept of DCS...

Please go through the queries again, may be you'll be able to understand what I am asking???

Regards,
Sameen

[katieburton12]

It is usually better to have autonomy at any given point in case communication gets disrupted, the task then could carry on of its own accord. If you have a central control system, it either means a lot of high speed data communication in a probable electrically noisy enviroment, or in a simpler form, a great deal of expensive interwiring. DCS is generally the preferred option.

[ali.abbas]

Agree with the reason given by katieburton. Here is how the Wikipedia defines a DCS, this should pretty much answer your question Sameen.

A distributed control system (DCS) refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location (like the brain) but are distributed throughout the system with each component sub-system controlled by one or more controllers.

Its quite evident from this that it is not the nature of plant control provided by the DCS due to which it has been termed so. It is in fact the architecture or modules design of the control system itself that is determining its generic name. The fact that a DCS is divided and sub-divided into multiple modules, each one responsible for its independent task (input, output, processing/controller functions, display/HMI functions, communications etc.) is why we call it distributed. And the advantage is quite clear that even if any particular module fails, it will not disrupt the overall control system operation, only the functionality of the affected module will be lost.