What is DCS? (Distributed Control System)

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Over the years, the term DCS has evolved from the original description for the acronym as a Distributed Control System to the use of the term Decentralized Control System and they seem to be somewhat interchangeable nowadays.

Briefly, as a point of the historical review, when PLC’s were invented, they were really good at handling single processes and were primarily used for repetitive, discrete control.

The advent of the DCS was for controlling many autonomous controllers that handled many continuous operations, mainly using analog control.

PLCs, traditionally, were used for single batch or high-speed control, have a relatively simple, low-cost design, and are the core of the system.

Processing time for tasks are typically very fast, operators usually interact and control the system using some sort of graphical display such as SCADA.

A DCS is used for continuous, complex controls, have an integrated control center much like a SCADA, which is the core of the system versus the processors in a PLC system.

The DCS has a number of predefined functions. Processing times are somewhat slower. Operators interact with the control system via an integrated graphical display.

DCS’s also have a claim that when safety is a top priority, the DCS is the most reliable system.

Redundancy may be deployed in either the PLC or DCS applications. You could employ redundant components to negate the possibility of process shutdowns.

Now that we’ve touched on some of the differences in the systems, let’s focus on the DCS and some of its components.

A typical plant starts with a centralized operator control center typically called Operator Stations.

This is where the operator can observe the operations of the plant, view process warnings and alarms, monitor production, and more.

The next level of components may contain servers, archiving computers, and engineering stations.
Communications with the Operator Station level is typically Industrial Ethernet.

Servers are used for the collection of data at the processor level.

Archiving computers are used for storing historical data that may be used for trends or compliance.

Engineering stations are used for creating the projects on which the processes run.

At the next level, you have the master controllers that supervise the individual processors as well as I/O modules.

The next level is the field device level.
Communications between this level and the processor level can be nearly any type that may be compatible with the components.

Components at this level would be devices such as transmitters, switches, valves, motors, remote or distributed I/O, etc.

In short, both PLCs and a DCS have their place in the market today.

PLCs would work best in a small production environment where component failure if no redundant system is deployed, is a small risk for the application, the budget is restricted, or the tasks and I/O count are minimal.

A DCS would be better used in an environment where there are large I/O counts with many continuous processes, a processor failure in one section of the plant is not a problem for production, or risk assessment has determined that an integrated package would be the best option.

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#RealPars #DCS #DistributedControlSystem

[mariaburman]

I'm a Project Manager/Mechanical Engineer currently running a control system project. This was such a great help. Thank you!😀

[halitekmekci]

I can say that as an automation engineer, the entire channel very informative. Thanks for it

[takashi]

I'm a Japanese young instrument engineer and I deeply appreciate your videos.

[qaiserbozdar]

Thank You very much and a lots of love from my side i am an Electronics Engineering Undergraduate, downloading your each Instrumentation Videos like this one and other such as sensors, VFD, motors etc. I am making a course from your videos for my Self learning.
Again Thank You, you are so helpful RealPars.

[paulbaribor]

I’m preparing for an instrumentation interview tomorrow and your page has been so helpful. Thank you.

[edswrivs]

It´s a very clear video, a lot of information organized, congrats REALPARS, you're so professionals, the automation field is very interesting, always i learn something new with you, thank you so much, greeting from Mexico!!

[avevaedgevideos]

Good video, as always. Just a clarification:

- You say that Industrial Ethernet is the way how Operation Stations and Servers (because you may also have redundant servers) communicate. This is correct; however, you’re using the PROFINET logo on that level which is wrong since not all the Industrial Ethernet communications are PROFINET.

You have all the entire schema based on Siemens hardware and software so we can have WinCC as example. Clients are connected by standard TCP/IP communications over Industrial Ethernet. In fact, it’s also common link the PLCs with the server using S7 Protocol over Industrial Ethernet instead of PROFINET.

PROFINET is more widely used on PLC <-> I/O or PLC <-> Intelligent Device/Sensor or even PLC <-> PLC communications since this protocol has huge advantages at this specific automation level.

[dr.alim.humada]

Excellent explanation, really it is very helpful for those work in control systems
(modern systems). Many thanks

[abdulgaffarmohammedshafee]

It is increased my technical knowledge & made my trade more happy

[solutionbybrain]

Firstly I would like to thanks realpars for all your videos that I looked in your channel, which I called it giving the secure key of all automation.
Secondly I would like to have details information about simatic IT with powerfull example regarding an example with management software ERP/PLM and madules MES function block library in simatic pcs7 v9.0 sp1 .

[basithpp]

thanks for the video.. its completely useful for me....all of your video's is different from other channels which i have seen.. explanation is very understandable
waiting for another content...

is there any course about automation providing by your team? please let me know

[akshaytalware]

Nice information... Requested you to please upload video on different protocol used for communicating third party system in automation...
E.g DCS to PLC

[qaiserbozdar]

It is requested to you that upload working and necessity of flobass computer S600+ and also about motorized and pneumatic valves. It will be helpful to me but also other electronics engineering pioneers.

[margamsravan]

Excellent video...mann....i really..appreciate for making this...pls explain elaborately about operating stations, and engeneering not forget to upload video on redundancy...

[san]

You forgot to mention that both plc and full cpus can be used in a dcs (for example ABB's dcs).

[epal]

great video very educational keep it up

[razikaaouir]

thank you so so much for this great work

[danielbarrantesvillalobos]

Hi, can you tell me what software do you use to the schematics & cabinets diagrams ?

[lyaeusv]

Hello I have a question sir what is the function of the server ? Does it convert the signal to something like OPC ua in order to communicate with control station and other machinery that are located far away ? Also the archive is it something like a Maria dab or sql database?
Great video btw !

[mouizimran]

Hi Sir,
Nice video.
1. Kindly make video on differences between PLC and DCS
2. Different communication protocols and their differences and pros and cons