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A SCADA (or supervisory control and data acquisition) system. It consists of many remote terminals units for collection of data (field),that is being connected with master station through any communication system, having main task of collection of accurate data and controlling of process for smooth operation.
It stands for distributed Control System, controlling is performed by embedded system (Microcontroller based or Microprocessor based controlling unit for device or instruments from which data is to be collect. It provides very intelligent analog control capability. It is very sensitive for HMI (Human machine Interface) for easy and smooth control of process.
It stands for Programmable Logic controller, having get this name from the fact that it replace the relay logic at the initial stage then it get the capability for analog channels also for display then it get the ability for close loop control and after some time it has the ability for redundant operation, and also its HMI having the ability for Indicatiion,controlling,data logging ,Alarming and backup data facility. It is also defined as below: “A digitally operating electronic apparatus which uses a programmable memory for the internal storage of instructions for implementing specific functions, such as logic, sequencing, timing, counting and arithmetic, to control through digital or analog input/output, various types of machines or process.” National Electrical Manufacturers Association (NEMA), 1978
PLC is used to control & perform the controlling activities over all the electrical/electronics/mechanical/pneumatic/hydraulic etc instruments & devices.Logic controller used mainly to interlock seeral kinds of different equipments used in a plant & process.PLC can be used on small or big scale individual machines.
SCADA is mainly used for data acquisition,monitoring of a process system.it used to collect the process monitored data & information.SCADA is not so much required on a individual machine automation. It is very important in big process /manufacturing operations.
DCS is used to control very very large process & operations flow bu using GUI.
If you are using, or planning to use, PLCs and HMI/ SCADA to control your process or batch applications, your application could be a candidate for the use of a DCS solution to help reduce costs and gain better control. The developer can concentrate on adding functionality that will provide more benefits, reducing the return on investment payback period and enhancing the system’s contribution for years to come. The divide between DCS and PLC/ SCADA approaches is wide, even though some commonality at the hardware level can be observed; the single database is at the heart of the DCS benefit and is a feature that holds its value throughout its life
ifference between PLC,DCS & SCADAIn the past the strength and weakness of both the automation technologies were well understood. So it was easy for engineers to select the one that suits their application, but now due to the advent of microprocessors both the technologies are merging.The requirements which are thought to be exclusive to one technology can be found in the other one too.But still there are some things which are to be checked out before selecting the one that suits your application the best.
Now a days you cannot really tell the difference between a PLC or a DCS. Since the PLC was integrated with Analog I/O it crosses the boundary of being just digital and crosses to the realm of DCS in handling Analogs, Bus Systems, Distributed I/O and etc. Also, since the DCS now handles logics of Digital I/O it also crossed the boundary to the realm of PLC.
As you know PLC as to its name Programmable Logic Controller. Its main purpose is to replace the relay logic controls which is "On" or "Off". And DCS "Distributed Control Systems" its emphasis is Fast analog handling because of communications through Bus systems, networking and etc.
Summarizing all these, PLC = DCS......BUT still there are basic differences as below
PLC is a programmable Logic controller which is used mainly for interlocking different equipments.PLC using for perticular mechine or production unit.PLC is economicaly low cost.PLC'S can handle analog and digital I/O as earliear it could handle only digital.PLC'S are automatic controllers which is a substitute to hard wired controllers.they are extensively used for automation.PLC is for stand alone sytem.PLC is used Commonly with On\\Off (Digital) Control and may be expanded with Analog I\\O Modules for Analog Control and used for a control task.Programmable Logic Controller
DCS: DISTRIBUTED CONTROL SYSTEMS: THIS SYSTEM DOES WHAT A PLC WOULD DO, BUT THE DIFFERENCE IS THAT A DCS IS USED IN MUCH LARGER AND COMPLEX APPLICATION E.G: POWER GENERATION, SOME COLD ROLLING MILLS etc.
DCS is the System in which controller are distributed geographically and integrated all the control hardwares .which is connected from the various field devices .DCS having its own network, Controller and HMI etc….Honeywell, Yokogawa, Invensys, ABB, Emerson are the leading .DCS Vendors.DCS is the System in which controller are distributed geographically and integrated all the control hardwares which is connected from the various field devices.DCS having its own network, Controller and HMI etc…Honeywell, Yokogawa, Invensys, ABB, Emerson are the leading DCS Vendors
Distributed Controller System
If taken from a narrow point of view, maybe PLC and DCS are functionally the same. However, a lot of plant technicians and engineers are not aware of the other side of the debate, namely the engineering effort and the commercial ramifications. Of course, for huge plants with I/O's ranging from 10,000 to 30,000 I/O points, and beyond, it is silly to even think about PLC. From my experience, a DCS is not the same with PLC in the realm of huge systems such as oil and gas plants, as the following list will show:
1. A PLC is cost-effective up to a certain I/O count, and so is the DCS. But the difference is in their starting points: the PLC is cost-effective from 0 to a few thousand I/O points; the DCS becomes cost-effective starting from a few thousand points and beyond.
2. A PLC becomes a subsystem of the DCS in rare occasions when the situation calls for it, i.e., purchase of huge package systems with engineering schedules incompatible with the DCS schedule (I/O lists cannot be submitted on time before the DCS hardware freeze date). Note that this package system is a process system using continuous control, not discrete. Based on this, a PLC can never be larger than a DCS in terms of I/O count.
3. In large plants the DCS is king because most owners want a single source of hardware support and service, and this mentality naturally denies the PLC a foothold. Package vendors are no longer required to provide PLC for their system. Everything is connected to the DCS.
SCADA: AS ALREADY EXPLAINED, IT NOTHING BUT A SOFTWARE USED TO GATHER DATA FROM THE FIELDS INSTRUMENTS WITH THE HELP OF YOUR DCS OR PLC DEPENDING ON THE APPLICATION VIA THE SERVER AND MAKING IT AVAILABLE IN AN ANIMATED FORM. THIS IS USUALLY FOUND IN YOUR CONTROL ROOMS AND DEVELOPMENT ROOM
SCADA
SCADA is the Software tool in which you can able to view/Monitor/Control your Process Variable data and Graphical representation of your plant etc...It's an operator front end display Example of few SCADA S/W is Wonderware, IFix, RS View, WinCC etcSCADA is Supervisory Control and Data Aquisition which is used to control and Monitor small number of Equipments in a field.SCADA systems are typically used to perform data collection and control at the supervisory level. Some systems are called SCADA despite only performing data acquisition and not control.The supervisory control system is a system that is placed on top of a real-time control system to control a process that is external to the SCADA system (i.e. a computer, by itself, is not a SCADA system even though it controls its own power consumption and cooling). This implies that the system is not critical to control the process in real time, as there is a separate or integrated real-time automated control system that can respond quickly enough to compensate for process changes within the time constants of the process
SCADA is the Software tool in which you can able to view/Monitor/Control your Process Variable data and Graphical representation of your plant etc...It's an operator front end displayExample of few SCADA S/W is Wonderware, IFix, RS View, WinCC etc
IN SHORT!
PLC:in manufacturing processes(for production of things)for simple batch control intensive logic controlscan handle a no. of I/O s at a timedowntime => lost productionusually,no need of redundancy fast logic scan(=reading I/Ps executing instructions and providing O/Ps)compacteasily customised for smaller applications
DCS:in process control (for production of stuff) for complex batch controladvanced analog loop controlsdowntime=>lost production+damage to process equipment+ may lead to dangerous conditionsso Redundancy mustlarge in sizecant be easily customisedfor larger applications and plant-wide
which is used mainly for interlocking different equipments. PLC using or particular machine or production unit. PLC is economically low cost.PLC'S can handle analog and digital I/O as earlier it could handle only digital.PLC'S are automatic controllers which is a substitute to hard wired controllers.they are extensively used for automation.PLC is for stand alone system.PLC is used Commonly with On\\Off (Digital) Control and may be expanded with Analog I\\O Modules for Analog Control and used for a control task.
PLC = DCS
this system does what a PLC would do, but DCS is used in much larger, complex and high accuracy applications. it can control large numbers of PLC's also.
hope you will the Meaning of Words for SCADA, DCS, PLC, and hope that you will they stands for, but when it comes to difference few will have knowledge , so far i know in SCADA is the latest version of DCS and PLC.
first was PLC, programmable logic control, mean that we used a micro controller to control a panel, or motor, instrument, anything u can , but the problem was that if we met any error the whole systems had to stopped, then the Engineers come with solution of DCS the distributed control system, in which for every function we used a different controller, so that in case of problem the whole must not stop, and remember that PLC and DCS was just supervisory. and then come the SCADA, Supervisory and acquisition of the data , in which you can control and every different part with different controllers. and the development feature was that you can send that data through satellite to other station or headquarter station , while DCS, PLC dose not offer that feature.
i am sorry for spelling mistakes and hope that you will be satisfy with my knowledge, if you found me wrong anywhere i am sorry for that as i am also fresh engineer in my carrier who has to still to get knowledge but what i have i shared with you.
thanks
plc is a programming which can we interface with different physical logic inputs and outputs,
scada is graphical interface with inputs and outputs with HMI (human machine interface ),
dcs is used for very large scale interfaces and eventually it used for remote areas,
A SCADA (or supervisory control and data acquisition) system.
DCS stands for distributed Control System, controlling is performed by embedded system (Microcontroller based or Microprocessor based controlling unit for device or instruments from which data is to be collect.
PLC stands for Programmable Logic controller
many expert have good answer
SCADA and DCS monitoring and controlling softwares, mainly their work to monitor levels, pressure, temperature, as human to process interface and to control will communicate with the machine through PLC sys.
While PLC its work as logical control system communicate and control the hardware (machine) directly through its I/O models.
