Placeholder Image

字幕列表 影片播放

  • In this video, we are going to do a deep dive into a DCS

  • and discuss some of the why's and how's associated with a DCS.

  • before we get started on today's video

  • if you love our videos,be sure to click the like button below.

  • then make sure to click subscribe

  • and the little bell to receive notifications of new RealPars videos.

  • This way you never miss another one!

  • Let's first clarify, for the purpose of this lesson, what we mean by DCS.

  • 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.

  • Regardless of which description is used,

  • we are discussing a structure that,at the high-level view,

  • is a system that coordinates and supervises an entire plant of many varying processes.

  • 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.

  • Through time and innovation,the lines have blurred a bit between the two systems

  • but each, in the current day, has some principal differences.

  • 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.

  • Their design is flexible and generic but completely customizable.

  • 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,

  • they 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 that come ready to customize

  • and deploy for various applications.

  • 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.

  • The reason for this is because the manufacturer supplies both the control and supervisory equipment

  • as an integrated package, the risks of integration errors are greatly reduced.

  • There are indeed scenarios in which a PLC system would be the best option such as smaller sized processes

  • where you could employ redundant components to negate the possibility of process shutdowns.

  • Without redundancy, you risk production halts due to the nature of a single processor controlling an entire plant.

  • Redundancy may be deployed in either the PLC or DCS applications.

  • We will talk more about redundancy in a future video.

  • Just as there are circumstances for a PLC system, the use of DCS would be for larger,more complex processes

  • that require a lot of interaction between many processors.

  • Now that we've touched on some of the differences in the systems,

  • let's focus on the DCS and some of its components.

  • The DCS is a process-oriented system that uses closed-loop control.

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

  • Operator Stations, in a DCS, are the heart of the system.

  • 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.

  • They are responsible for the data that moves between the Operator Station and the processors on the plant floor.

  • 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.

  • This includes hardware configurations, logic for tasks, graphical displays for operator interaction,

  • and the administration of all of those tasks through installed software packages.

  • This is the station that is used to download the projects to the processors and the graphical displays.

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

  • These controllers are also responsible for providing the data to the servers,

  • which in turn, supply the data for the graphical interface.

  • Industrial Ethernet is typically used for communication with the previous level.

  • Fiber Optic may be used here when Ethernet cabling runs would be too long.

  • At this level, the processor executes the logic and does what it needs to do in order to control the process.

  • 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.

  • Those include Industrial Ethernet, Profibus DP, EtherCAT,

  • Fiber Optic, or other proprietary communication protocols.

  • 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.

  • The line between the two systems is nearly invisible nowadays

  • and it may not be long before there is no differentiation at all.

  • In future videos, we are going to discuss SCADA and contrast DCS and SCADA systems so stay tuned!

  • Want to learn PLC programming in an easy to understand format

  • and take your career to the next level?

  • Head on over to realpars.com

In this video, we are going to do a deep dive into a DCS

字幕與單字

影片操作 你可以在這邊進行「影片」的調整,以及「字幕」的顯示

B1 中級 美國腔

什麼是DCS?(分佈式控制系統) (What is DCS? (Distributed Control System))

  • 29 4
    蔡育德 發佈於 2021 年 01 月 14 日
影片單字