What exactly is a distributed control system?

A Distributed Control System (DCS) is a control technology that relies on multiple microprocessors, and utilizes modern network technologies, advanced control techniques, graphic display technologies, and redundancy techniques to regulate, monitor, and manage dispersed control objects. Its feature is to use decentralized control to adapt to decentralized control objects, and to achieve overall oversight through centralized monitoring and operation. The system features high stability, reliability, and scalability. 　　A distributed control system generally consists of four parts: (1) process input/output devices ； (2) Process control device ； (3) Operation interface ； (4) Data communication system. 　　A distributed control system, also known as a distributed control architecture, is a new type of computer-based control system as opposed to centralized control systems; it has evolved from centralized control systems. In terms of system functionality, there is little difference between DCS and centralized control systems, but their approaches to implementing system functions are completely different. 　　Firstly, the backbone of DCS is the system network, which serves as its foundation and core. Since the network plays a decisive role in the real-time performance, reliability, and scalability of the entire DCS system, manufacturers have invested considerable effort in its careful design. For the system network of DCS, it must meet real-time requirements, that is, to complete the transmission of information within a specified time limit. The time limit referred to as “determined” here means that information transmission can be completed within this time limit under any circumstances, and this time limit is determined based on the real-time requirements of the controlled process. Therefore, the indicator for measuring the performance of a system network is not the network’s speed, that is, the number of bits per second (bps), but rather the real-time performance of the system network, that is, how quickly it can ensure the transmission of the required information is completed. The system network must also be highly reliable; network communication must not be interrupted under any circumstances. Therefore, most manufacturers’ DCS systems employ network topologies such as dual-bus, ring, or dual-star configurations. To meet the requirements for system scalability, the maximum number of nodes that can be connected to the system network should be several times higher than the actual number of nodes in use. In this way, new nodes can be added at any time on the one hand, while on the other hand it allows the system network to operate with a lower communication load, thereby ensuring the real-time performance and reliability of the system. During the actual operation of the system, connections to and from the network can occur at any time, especially at the operator station. As a result, network reconfiguration takes place frequently, and such operations must not affect the normal functioning of the system. Therefore, the system’s network should have a strong capability for online network reconfiguration. 　　Secondly, it is a network node that handles on-site I/O entirely and implements direct digital control (DOS) functionality. Typically, a set of DCS includes field I/O control stations, which are used to handle the I/O and control functions of the entire system. This not only prevents the entire system from failing due to the failure of a single site, thereby improving system reliability, but also allows each site to share the tasks of data collection and control, which helps to enhance the performance of the entire system. The operator station of a DCS is a network node that handles all human-machine interface (HMI – Human Machine Interface or operator interface) functions related to operational control. 　　The system network is the engineer station of the DCS; it is a network node used for offline configuration and setup of the DCS, as well as for online monitoring, control, and maintenance of the system. Its main functions are to provide software tools for configuring the DCS, and to monitor in real time the operation of various nodes on the DCS network while it is running. This allows system engineers to adjust the system configuration and various parameters promptly through the engineer station, ensuring that the DCS remains in its optimal operating condition at all times. Unlike centralized control systems, all DCS systems require a system configuration function; it can be said that a system without such a function cannot be called a DCS. 　　Since its introduction in 1975, DCS has gone through more than two decades of development. Over these more than twenty years, although there have been no major changes in the architectural structure of DCS, its functions and performance have improved significantly through continuous development and refinement. Overall, DCS is moving toward being more open, more standardized, and more product-oriented. 　　As a computer control system in the field of production process automation, the traditional DCS is merely a narrow concept. If one assumes that DCS is merely an automation system for production processes, it will lead to incorrect conclusions, as the meaning of modern computer control systems has been **expanded**. These systems include not only everything that was once part of DCS, but also extend down to each measuring device and actuator on the factory floor, and upward to production management and all aspects of business operations. In the traditional sense, DCS now refers only to the automation of the production process control aspect, whereas the concept of an industrial automation system should be viewed as a comprehensive solution for enterprises, that is, at the level of a total solution. Only by raising and solving problems from this perspective can computer automation truly fulfill its intended role. 　　After entering the 1990s, computer technology advanced by leaps and bounds, and more new technologies were applied to DCS. A PLC is an electronic device developed for sequential logic control, primarily used to replace inflexible and bulky relay logic. Fieldbus technology developed at a rapid pace after the mid-1990s, to the point that some people predicted that FCS based on fieldbuses would replace DCS as the dominant control system. The above resources are from the Internet! This post was last edited by wopale3 on 2009-3-27 20:38]

　　 DCS stands for Distributed Control System; in China it is commonly referred to as a distributed control and monitoring system. DCS is a multi-level computer system composed of a process control level and a process monitoring level, connected by a communication network. It integrates the four C technologies of computing, communication, display, and control. Its basic principles are decentralized control, centralized operation, hierarchical management, flexible configuration, and easy setup. DCS has the following characteristics: (1) High reliability. Since DCS distributes system control functions across various computers, and the system architecture features fault tolerance, a failure in one computer does not result in the loss of other system functions. Furthermore, since the tasks performed by each computer in the system are relatively simple, dedicated computers with specific architectures and software can be used for the functions that need to be implemented, thereby improving the reliability of each computer in the system as well. 　　 (2) Openness. DCS features an open, standardized, modular, and serialized design. The computers within the system communicate with each other via a local area network to enable information transfer. When it is necessary to modify or expand the system’s functions, new computers can be easily connected to the system’s communication network or removed from it, with little impact on the operation of the other computers in the system. 　　 Definition of DCS 　　 DCS is the abbreviation for Distributed Control System; in China’s automation industry, it is also referred to as a distributed control system. 　　It is a multi-level computer system composed of a process control level and a process monitoring level, connected by a communication network. It integrates the 4C technologies of Computer, Communication, CRT, and Control. Its basic philosophy is decentralized control, centralized operation, hierarchical management, flexible configuration, and easy setup. ) After entering the 1990s, computer technology advanced by leaps and bounds, and more new technologies were applied to DCS. A PLC is an electronic device developed for sequential logic control, primarily used to replace inflexible and bulky relay logic. Fieldbus technology developed at a rapid pace after the mid-1990s, to the point that some people predicted that FCS based on fieldbuses would replace DCS as the dominant control system. 　　DCS is the abbreviation for Data Communication Subsystem. 　　Taking the rail transit industry as an example, DCS is a completely transparent non-safety system that serves as a medium for transmitting messages between the control center and the trains. 　　The second meaning of DCS: Dorsal Column Stimulator, a spinal stimulation device. In fields requiring specialized control, such as nuclear power plant control systems, DCS stands for Digital Control System. 　　The main domestic DCS manufacturers include Zhejiang University Zhongkong, HollySys (Beijing, Hangzhou), and Shanghai Xinhua. Abroad, there are Yokogawa Corporation, Honeywell Corporation, FOXBORO Company, Yamatake-Honeywell Corporation, and FISHER-ROSEMOUNT Company. Overview of the characteristics and development of DCS: DCS stands for Distributed Control System; in China, it is generally referred to as a distributed control system. It is a multi-level computer system composed of a process control level and a process monitoring level, connected by a communication network. It integrates the 4C technologies of Computer, Communication, CRT, and Control. Its basic philosophy is decentralized control, centralized operation, hierarchical management, flexible configuration, and easy setup. 　　　 DCS has the following characteristics: (1) High reliability. Since DCS distributes system control functions across various computers, and its system architecture features fault-tolerant design, a failure in one computer does not result in the loss of other system functions. Furthermore, since the tasks performed by each computer in the system are relatively simple, dedicated computers with specific architectures and software can be used for the functions that need to be implemented, thereby improving the reliability of each computer in the system as well. 　(2) Open DCS adopts an open, standardized, modular, and serialized design. The computers within the system communicate with each other via a local area network to enable information transfer. When it is necessary to modify or expand the system’s functions, new computers can be easily connected to the system’s communication network or removed from it, with little impact on the operation of the other computers in the system. 　　 (3) Flexibility: Through configuration software, hardware and software can be configured according to different process applications, that is, by determining the measurement and control signals as well as their interconnections, selecting appropriate control rules from a control algorithm library, and invoking basic graphics from a graphic library to create the various monitoring and alarm displays required, thereby facilitating the creation of the desired control system. 　　 (4) Easy to maintain: Small or micro specialized computers with simple functions are easy to maintain; when a certain component or computer fails, it can be replaced online without affecting the operation of the entire system, allowing for rapid fault resolution. 　　 (5) Coordination: Various data are transmitted between the different workstations via a communication network, enabling information sharing across the entire system and coordinated operation in order to fulfill the overall functions of the control system and optimize its performance. 　　 (6) It has comprehensive control functions and a rich variety of control algorithms. It integrates continuous control, sequential control, and batch processing control, and enables advanced control methods such as cascade control, feedforward control, decoupling control, adaptive control, and predictive control. It also allows for the easy addition of any special control algorithms required. The configuration of DCS is highly flexible; it can be composed of dedicated management computer stations, operator stations, engineer stations, recording stations, field control stations, and data acquisition stations, or it can be built using general-purpose servers, industrial control computers, and programmable controllers. The process control level at the lowest tier typically carries out data acquisition and control locally through dispersed field control stations, data acquisition stations, etc., and transmits the data to the production monitoring level computers via a data communication network. The production monitoring level performs centralized operation and management of data from the process control level, such as various optimization calculations, statistical reports, fault diagnosis, and alarm display. With the development of computer technology, DCS can be connected to higher-performance computer devices via a network as needed, thereby enabling more advanced centralized management functions such as scheduling, warehouse management, and energy management. 　　 The development and application status of DCS at home and abroad: In 1975, Honeywell, the largest instrument control company in the United States, introduced its integrated distributed control system, TDC-2000 (Total Distributed Control-2000), to the world for the first time. The introduction of this system immediately received high praise from the industrial control community in the United States, which described it as \"the most inspiring event\". Major companies around the world followed suit, introducing one after another distributed control systems, and process control thus entered a new era marked by these distributed systems. 　　 During this period, there were CEN TUM launched by the Japanese company Yokogawa, MO SË from the American company Taylor Instruments, DCÉ-400 from Fisher Company, N-90 from Bailey Company, Cpectrum from Foxboro Company, and Telepermm from the German company Siemens. 　　With the rapid development of computers, especially microcomputers, and network technology, coupled with fierce competition among manufacturers, DCS evolved rapidly from the first generation in the 1970s to the third generation of DCS by the early 1990s. Although the technical level of distribution systems was already high at that time, there was one major drawback: the dozens of different models of systems offered by various companies were almost all patented products belonging to those companies themselves. In order to protect their own interests, each company relied on patent networks, which created problems for the management of entire factories and enterprises. 　　With the development of computers and network technology, various control manufacturers began to make greater use of commercial computer technologies. At the end of the 1980s, many companies introduced a new generation of distributed control systems, whose main features were the use of the MAP protocol for the local networks of these systems; the adoption of intelligent transmitters and fieldbus architectures; and the incorporation of PLC-based sequential and batch control functions into the control software, thereby enabling DCS systems to possess the same functions as PLCs. 　　 By the early 1990s, the well-known DCS systems in various countries included: 3000, Bailey’s INFI-90, Rossumunt’s RS-3, West House’s WDPF, Leeds & Nothern’s MAX-1000, Foxboro’s I/OAS, and Yokogawa of Japan’s CENTUM. All those mentioned here are large-scale DCS systems; to meet market demands, various manufacturers have also developed many smaller and medium-sized DCS systems such as S-9000, MAX-2, LXL, A2 PACS, and so on.

In a word, it’s very simple: a distribution system means centralized management and decentralized control

In my understanding, it involves gathering the scattered signals from the on-site meters and bringing them together on a computer for control, that is, centrally controlling the scattered signals coming from the site

My layman’s understanding: Collection: centralized management and centralized monitoring. Scattered: The system can have multiple process stations, each controlling different devices to achieve decentralized control. That is, the upper-level machine belongs to the “collective” category, while the lower-level machines belong to the “dispersed” category”

I have a slight disagreement; the phrase should be: centralized control, decentralized risk

Centralized control and management, decentralized control of devices

DCS translates literally to “Distributed Control System,” but “distributed control” is a more vivid description; it refers to centralized operation and management, along with decentralized control and dispersion of risks.

In reality, it means centralized control with dispersed risks!

Centralized control, decentralized risk: Specifically, when a part of the system fails, it does not affect the normal operation of the entire system.

DCS is the abbreviation for Distributed Control System; in China’s automation industry, it is also referred to as a distributed control system. 　　The so-called distributed control system, or referred to as a distributed control system in some literature, is a new type of computer-based control system as opposed to centralized control systems; it has developed and evolved from centralized control systems. In terms of system functionality, there is little difference between DCS and centralized control systems, but their approaches to implementing system functions are completely different. 　　Firstly, the backbone of DCS is the system network, which serves as its foundation and core. Since the network plays a decisive role in the real-time performance, reliability, and scalability of the entire DCS system, manufacturers have invested considerable effort in its careful design. For the system network of DCS, it must meet real-time requirements, that is, to complete the transmission of information within a specified time limit. The time limit referred to as “determined” here means that information transmission can be completed within this time limit under any circumstances, and this time limit is determined based on the real-time requirements of the controlled process. Therefore, the indicator for measuring the performance of a system network is not the network’s speed, that is, the number of bits per second (bps), but rather the real-time performance of the system network, that is, how quickly it can ensure the transmission of the required information is completed. The system network must also be highly reliable; network communication must not be interrupted under any circumstances. Therefore, most manufacturers’ DCS systems employ network topologies such as dual-bus, ring, or dual-star configurations. To meet the requirements for system scalability, the maximum number of nodes that can be connected to the system network should be several times higher than the actual number of nodes in use. In this way, new nodes can be added at any time on the one hand, while on the other hand it allows the system network to operate with a lower communication load, thereby ensuring the real-time performance and reliability of the system. During the actual operation of the system, connections to and from the network can occur at any time, especially at the operator station. As a result, network reconfiguration takes place frequently, and such operations must not affect the normal functioning of the system. Therefore, the system’s network should have a strong capability for online network reconfiguration. 　　Secondly, it is a network node that handles on-site I/O entirely and implements direct digital control (DOS) functionality. Typically, a set of DCS includes field I/O control stations, which are used to handle the I/O and control functions of the entire system. This not only prevents the entire system from failing due to the failure of a single site, thereby improving system reliability, but also allows each site to share the tasks of data collection and control, which helps to enhance the performance of the entire system. The operator station of a DCS is a network node that handles all human-machine interface (HMI – Human Machine Interface or operator interface) functions related to operational control. 　　The system network is the engineer station of the DCS; it is a network node used for offline configuration and setup of the DCS, as well as for online monitoring, control, and maintenance of the system. Its main functions are to provide software tools for configuring the DCS, and to monitor in real time the operation of various nodes on the DCS network while it is running. This allows system engineers to adjust the system configuration and various parameters promptly through the engineer station, ensuring that the DCS remains in its optimal operating condition at all times. Unlike centralized control systems, all DCS systems require a system configuration function; it can be said that a system without such a function cannot be called a DCS. 　　Since its introduction in 1975, DCS has gone through more than two decades of development. Over these more than twenty years, although there have been no major changes in the architectural structure of DCS, its functions and performance have improved significantly through continuous development and refinement. Overall, DCS is moving toward being more open, more standardized, and more product-oriented. 　　As a computer control system in the field of production process automation, the traditional DCS is merely a narrow concept. If one assumes that DCS is merely an automation system for production processes, it will lead to incorrect conclusions, as the meaning of modern computer control systems has been **expanded**. These systems include not only everything that was once part of DCS, but also extend down to each measuring device and actuator on the factory floor, and upward to production management and all aspects of business operations. In the traditional sense, DCS now refers only to the automation of the production process control aspect, whereas the concept of an industrial automation system should be viewed as a comprehensive solution for enterprises, that is, at the level of a total solution. Only by raising and solving problems from this perspective can computer automation truly fulfill its intended role. 　　DCS stands for Distributed Control System; in China it is commonly referred to as a distributed control and monitoring system. DCS is a multi-level computer system composed of a process control level and a process monitoring level, connected by a communication network. It integrates the four C technologies of computing, communication, display, and control. Its basic principles are decentralized control, centralized operation, hierarchical management, flexible configuration, and easy setup. DCS has the following characteristics: (1) High reliability. Since DCS distributes system control functions across various computers, and the system architecture features fault tolerance, a failure in one computer does not result in the loss of other system functions. Furthermore, since the tasks performed by each computer in the system are relatively simple, dedicated computers with specific architectures and software can be used for the functions that need to be implemented, thereby improving the reliability of each computer in the system as well. 　　(2) Openness. DCS features an open, standardized, modular, and serialized design. The computers within the system communicate with each other via a local area network to enable information transfer. When it is necessary to modify or expand the system’s functions, new computers can be easily connected to the system’s communication network or removed from it, with little impact on the operation of the other computers in the system. 　　Definition of DCS 　　DCS is the abbreviation for Distributed Control System; in China’s automation industry, it is also referred to as a distributed control system. 　　It is a multi-level computer system composed of a process control level and a process monitoring level, connected by a communication network. It integrates the 4C technologies of Computer, Communication, CRT, and Control. Its basic philosophy is decentralized control, centralized operation, hierarchical management, flexible configuration, and easy setup. ) After entering the 1990s, computer technology advanced by leaps and bounds, and more new technologies were applied to DCS. A PLC is an electronic device developed for sequential logic control, primarily used to replace inflexible and bulky relay logic. Fieldbus technology developed at a rapid pace after the mid-1990s, to the point that some people predicted that FCS based on fieldbuses would replace DCS as the dominant control system. 　　DCS is the abbreviation for Data Communication Subsystem. 　　Taking the rail transit industry as an example, DCS is a completely transparent non-safety system that serves as a medium for transmitting messages between the control center and the trains. 　　The second meaning of DCS: Dorsal Column Stimulator, a spinal stimulation device. In fields requiring specialized control, such as nuclear power plant control systems, DCS stands for Digital Control System. 　　The main domestic DCS manufacturers include: Shanghai Xinhua, Luneng Control, Guodian Zhishen, Zhejiang University Control System, HollySys, Shanghai Huawen, Shanghai Lehua, Zhejiang Zhongzi, etc. Abroad, there are companies such as Westinghouse (Emerson), FOXBORO, ABB, Siemens, Honeywell, Yokogawa, Yamatake-Honeywell, and FISHER-ROSEMOUNT. Overview of the characteristics and development of DCS: DCS stands for Distributed Control System; in China, it is commonly referred to as a distributed control system. It is a multi-level computer system composed of a process control level and a process monitoring level, connected by a communication network. It integrates the 4C technologies of Computer, Communication, CRT, and Control. Its basic philosophy is decentralized control, centralized operation, hierarchical management, flexible configuration, and easy setup. 　　　DCS has the following characteristics: (1) High reliability. Since DCS distributes system control functions across various computers, and its system architecture features fault-tolerant design, a failure in one computer does not result in the loss of other system functions. Furthermore, since the tasks performed by each computer in the system are relatively simple, dedicated computers with specific architectures and software can be used for the functions that need to be implemented, thereby improving the reliability of each computer in the system as well. 　　(2) Open DCS adopts an open, standardized, modular, and serialized design. The computers within the system communicate with each other via a local area network to enable information transfer. When it is necessary to modify or expand the system’s functions, new computers can be easily connected to the system’s communication network or removed from it, with little impact on the operation of the other computers in the system. 　　(3) Flexibility: Through configuration software, hardware and software can be configured according to different process applications, that is, by determining the measurement and control signals as well as their interconnections, selecting appropriate control rules from a control algorithm library, and invoking basic graphics from a graphic library to create the various monitoring and alarm displays required, thereby facilitating the creation of the desired control system. 　　(4) Easy to maintain: Small or micro specialized computers with simple functions are easy to maintain; when a certain component or computer fails, it can be replaced online without affecting the operation of the entire system, allowing for rapid fault resolution. 　　(5) Coordination: Various data are transmitted between the different workstations via a communication network, enabling information sharing across the entire system and coordinated operation in order to fulfill the overall functions of the control system and optimize its performance. 　　(6) It has comprehensive control functions and a rich variety of control algorithms. It integrates continuous control, sequential control, and batch processing control, and enables advanced control methods such as cascade control, feedforward control, decoupling control, adaptive control, and predictive control. It also allows for the easy addition of any special control algorithms required. The configuration of DCS is highly flexible; it can be composed of dedicated management computer stations, operator stations, engineer stations, recording stations, field control stations, and data acquisition stations, or it can be built using general-purpose servers, industrial control computers, and programmable controllers. The process control level at the lowest tier typically carries out data acquisition and control locally through dispersed field control stations, data acquisition stations, etc., and transmits the data to the production monitoring level computers via a data communication network. The production monitoring level performs centralized operation and management of data from the process control level, such as various optimization calculations, statistical reports, fault diagnosis, and alarm display. With the development of computer technology, DCS can be connected to higher-performance computer devices via a network as needed, thereby enabling more advanced centralized management functions such as scheduling, warehouse management, and energy management. 　　The development and application status of DCS at home and abroad. In 1975, Honeywell, the largest instrument control company in the United States, introduced its integrated distributed control system, TDC-2000 (Total Distributed Control-2000), to the world for the first time. The introduction of this system immediately received high praise from the industrial control community in the United States, which described it as \"the most inspiring event\". Major companies around the world followed suit, introducing one after another distributed control systems, and process control thus entered a new era marked by these distributed systems. 　　During this period, there were CEN TUM launched by the Japanese company Yokogawa, MO SË from the American company Taylor Instruments, DCÉ-400 from Fisher Company, N-90 from Bailey Company, Cpectrum from Foxboro Company, and Telepermm from the German company Siemens. 　　With the rapid development of computers, especially microcomputers, and network technology, coupled with fierce competition among manufacturers, DCS evolved rapidly from the first generation in the 1970s to the third generation of DCS by the early 1990s. Although the technical level of distribution systems was already high at that time, there was one major drawback: the dozens of different models of systems offered by various companies were almost all patented products belonging to those companies themselves. In order to protect their own interests, each company relied on patent networks, which created problems for the management of entire factories and enterprises. 　　With the development of computers and network technology, various control manufacturers began to make greater use of commercial computer technologies. At the end of the 1980s, many companies introduced a new generation of distributed control systems, whose main features were the use of the MAP protocol for the local networks of these systems; the adoption of intelligent transmitters and fieldbus architectures; and the incorporation of PLC-based sequential and batch control functions into the control software, thereby enabling DCS systems to possess the same functions as PLCs. 　　By the early 1990s, the well-known DCS systems in various countries included: 3000, Bailey’s INFI-90, Rossumunt’s RS-3, West House’s WDPF, Leeds & Nothern’s MAX-1000, Foxboro’s I/OAS, and Yokogawa of Japan’s CENTUM. All those mentioned here are large-scale DCS systems; to meet market demands, various manufacturers have also developed many smaller and medium-sized DCS systems such as S-9000, MAX-2, LXL, A2 PACS, and so on. 　　The main DCS systems available in China at present include Xinhua XDPS, Luneng’s LN2000, Guodian Zhishen DCS, Zhongkong DCS, Hollyland DCS, and Zhejiang Zhongzi, among others. Abroad, there are Westinghouse (Emerson) Ovation, FOXBORO, ABB, Siemens PCS7, Honeywell, and Yokogawa DCS

A single character difference can lead to a huge difference in meaning. Here, \"ji\" does not refer to centralized control, but rather \"centralized operation\", as opposed to the decentralized operation of instruments mounted on analog panels. Extending this concept, there is also centralized data processing and centralized report management; the units that carry out these functions are known as operation stations. On the other hand, \"san\" refers to the control units (stations) that perform control functions, with all process controls taking place there. Since each control unit is responsible for controlling a specific process, multiple units work together to control the entire device, resulting in a relatively decentralized configuration. This is not only required by the system architecture but can also be seen as a way to distribute the risks associated with control

1. Personally, I think centralized control refers to the centralized management of various dispersed devices; the components on-site are spread out, but they are all managed through a single system. 2. DCS is a concept or management control idea that was proposed quite early on; nowadays its applications are expanding, and the original concepts have become somewhat narrow. 3. The question raised by Banzhu: Whether the lower-level system should be integrated or decentralized. Personally, I feel that the lower-level machine is both integrated and decentralized. For local control on a small scale, it is centralized – for example, the control system of a compressor or that of a dryer; in terms of the individual devices, this represents centralized management and control. However, for the entire installation as a whole, it constitutes one component of a larger control system. 4. The host computer is also part of the centralized management; is it the “visible” part? A friend introduced me to this forum; it seems nice. Hehe, learned from everyone*:loveliness:

You don’t know until you see it; once you do, it’s clear. Thank you

Introduced by a friend; I started learning *, thank you! :)