1、 A typical DCS control system DCS (Distributed control system) is a microprocessor-based centralized onitoring of the production process, operation, management, centralized and decentralized control of distributed control system, called DCS. The system will be used in a number of units distributed p
2、rocess control computer, all information through the communication network by the host management computer monitor, to achieve optimal control, the device inherits the conventional instrument distributed control and the advantages of computer control to overcome the normal function of a single instr
3、ument, Human - Machine Contact poor and the single risk of micro-computer control system of a high concentration of defects, both achieved in the management, operation and display of three concentrate, but also realized in functionality, load and risk of spread in three areas. DCS system in the mode
4、rn production process control plays an important role. Distributed control systems typically have the following four components: Field control level known as data acquisition devices, mainly the non-control variables during data acquisition and preprocessing, and further processing of real-time data
5、 for the CRT display and print operation station, in order to achieve open-loop monitoring, and collected data to monitoring computer. Output device in a PC case, or can switch analog signals the way the computer output to the terminal device control commands. This is one level directly to the scene
6、, the process is connected with the site. Such as valves, motors, sensors, transmitters, actuators and so on. They are the basis for industrial field device, it is also the basis of DCS. In the DCS system, this level of function is to obey the commands sent by the host computer, while upward-bit mac
7、hine feedback implemented. Take for example the armed forces to the case, can be described as the bottom of the soldiers. They just follow orders accurately and precisely report the situation to higher authorities to complete the mission. As for its exchange with the host computer is through the ana
8、log signal or fieldbus digital signal. Because analog signals in the transmission process, there are some more or less distortion or interference, so by popular fieldbus for DCS signals. Process control level Also known as the basic field control unit or controller, is the core part of the DCS syste
9、m. Relied on the regulation of production processes are achieved. Such as regulating the opening and closing valves, sequence control, continuous control and so on. Speaking of field control level is above the soldiers, then it is in command of the process control level. It accepts signals coming fr
10、om field control level, control law in accordance with the requirements of computing technology, and the results sent to the scene as a control signal level control device. Therefore, the process control level to have a smart brain, able to soldiers to analyze the feedback of the military, and then
11、make an order to make the soldiers can win war. his level is not the highest, equivalent to the armys lieutenant. It must be the same site feedback to a higher level of Colonel is the following about the process management level. Process management level DCS man-machine interface device, generally w
12、ith a high resolution, large screen color CRT, the operator keyboard, printer, mass storage and so on. Select the operator station through the operation of various operating and monitoring production, This level is the operator with the DCS platform for exchange of information. DCSs core is shown op
13、erating with the management device. Operator through the operator station to monitor and control the production process, production can be learned through the operation of the screen to see the number of process variables with each state. This level be high in the armed forces, Colonel was. Its poss
14、ession of power as needed to manually switch automatically at any time, modify the settings, adjust the control signals, control field devices to achieve the control of the production process. Management level Also known as the host computer, features, speed, large capacity. Through dedicated commun
15、ication interface and high-speed data path connected, integrated surveillance system unit, and managing all system information. This is the highest whole plant floor automation systems. Only large-scale distributed control system is qualified for this level. The military equivalent of the Marshal, t
16、hey are for the user is a director, manager, chief engineer and other administrative or operational management personnel. Its a great privilege, you can monitor the operation of various departments, the use of historical data and real-time data to predict the various situations that may occur from t
17、he overall interests of business to help business executives make decisions to help companies achieve their program objectives. DCS system background 40s 30s last century, industrial automation equipment is used in dispersion control system. All equipment is run independently, not networked control.
18、 Operator calculated based on production requirements, will be independent of device characteristics to the appropriate level of regulation, and then began to work. After using a pneumatic, electric analog instrument into the process control system, a certain degree of centralized monitoring, operat
19、ion and decentralized control. Better adapted to the needs of industrial production. However, with the production scale and complexity of the continuous improvement of the existing control system appears to lag, heavy, cumbersome, because a meter is only one control law to achieve some of the comple
20、x control is difficult. In addition, an increasing number of control instruments, using the original control of the instrument panel behind the words, the control panel and longer, to see peoples eyes will be spent. The most deadly is the old systems are not easy to implement communication, control
21、and integrated management of difficult classification. Another is that it is too much trouble to change the system only changes through the replacement of meters and meter connections can be achieved. After the beginning of the third technological revolution, with the development of computer technol
22、ogy, people began to try to computers for process control. Have tried to use the computer features, to overcome the limitations of conventional analog gauges. But then the approach is to use a computer control dozens or even hundreds of loops, a high risk of doing so, if the computer fails, will lea
23、d to very serious consequences, and this is the so-called dangerous concentration. The use of a dual-duplex system, although you can improve system reliability, but the cost is too high, if the factorys production is small, then the economy is poor, the user is difficult to accept. Until the last ce
24、ntury, 70 years, with increasingly sophisticated computer technology, the birth of large scale integrated circuits and microprocessors, people can start thinking about whether the dangerous spread. NTU is the original by a computer to complete the arduous task, can use dozens of micro-processing to
25、complete? In this case, even if a processor is broken, that does not will affect the situation as a whole, so that greatly reduced the risk coefficient. The answer is yes. Thus was born the DCS. Into the next decade, computer technology advances, more new technology is being applied to the DCS. PLC is a sequential logic control developed for electronic equipment, which is used instead of inflexible and cumbersome relay logic. Fieldbus
