DCS系统又称为DCS控制系统（Distributed Control System），即集散控制系统，是以微处理器为基础，采用控制功能分散、显,示操作集中、兼顾分而自治和综合协调的设计原则的新一代仪表控制系统。集散控制系统简称DCS，也可直译为“分散控制系统”或“分布式计算机控制系统”。
DCS system, also known as distributed control system (DCS), is a new generation of instrument control system based on microprocessor, which adopts the design principles of decentralized control function, display, centralized operation, taking into account the division and autonomy and comprehensive coordination. Distributed control system (DCS) is also called "distributed control system" or "distributed computer control system".
DCS adopts the basic design idea of decentralized control, centralized operation and management, and adopts the structure of multi-layer classification, cooperation and autonomy. Its main feature is its centralized management and decentralized control. At present, DCs has been widely used in electric power, metallurgy, petrochemical and other industries.
DCS hardware architecture:
(1) Field control unit
The field control unit is usually far away from the control center and installed near the site. Its highly modular structure can be configured into process control units with different scales from several monitoring points to hundreds of monitoring points according to the needs of process monitoring and control. The structure of the field control unit is composed of a lot of boards (or cards) with scattered functions, which are installed in the board box according to a certain logical or physical order. Each field control unit and its control management level are connected by bus to realize information exchange.
现场控制单元的硬件配置需要完成以下内容：插件的配置 根据系统的要求和控制规模配置主机插件（CPU插件）、电源插件、I/O插件、通信插件等硬件设备；硬件冗余配置 对关键设备进行冗余配置是提高DCS可靠性的一个重要手段，DCS通常可以对主机插件、电源插件、通信插件和网络、关键I/O插件都可以实现冗余配置。
The hardware configuration of the field control unit needs to complete the following contents: configuration of plug-ins; configuration of host plug-ins (CPU plug-ins), power plug-ins, I / O plug-ins, communication plug-ins and other hardware devices according to the system requirements and control scale; hardware redundancy configuration Redundancy configuration of key equipment is an important means to improve the reliability of DCS. DCs can usually achieve redundancy configuration of host plug-in, power plug-in, communication plug-in, network plug-in and key I / O plug-in.
The hardware installation of DCS is different. For the installation of various plug-ins in the plug-in box, there will be corresponding provisions in the logical sequence or physical sequence. In addition, the field control unit is usually divided into basic type and extended type. The so-called basic type is that all kinds of plug-ins are installed in a plug-in box, but more often it needs an extensible structure, that is, a field control unit also includes several digital input / output expansion units, which are connected by bus. In essence, the structure and configuration requirements of field control unit are consistent with the hardware configuration of modular PLC.
(2) Operation station
The operation station is used to display and record the process data from each control unit, and it is the operation interface of human and production process information interaction. Typical operation station includes host system, display device, keyboard input device, information storage device and print output device, which mainly realizes powerful display function (such as analog parameter display, system status display, multiple screen display, etc.), alarm function, operation function, report printing function, configuration and programming function, etc.
In addition, DCS operation station is divided into operator station and engineer station. From the perspective of system function, the former mainly realizes the general production operation and monitoring tasks, and has the functions of data acquisition and processing, monitoring screen display, fault diagnosis and alarm. In addition to the general functions of the operator station, the latter should also have the functions of system configuration and control target modification. From the point of view of hardware equipment, the engineer station and operator station of most systems are combined, and only one engineer keyboard is used to distinguish them.