PLC和DCS_中英文翻译_论文.doc

翻译原文 DCS principle and PLC foundationDCS principle and PLC foundationDCS principle Distributed Control System (DCS) carries on the centralism monitor, the operation, the management and the disperser control which is one kind of new control technology using the computer technology to the production process. DCS is base on the computer technology, the signal processing technology, the survey control technology, the correspondence network technology, the CRT technology, the graphical display technology and the man-machine connection technology mutually seeps the development to produce. DCS both is different with the dispersible measuring appliance control, and different with Yuji Chinese type computer control system, but overcomes the two flaw to concentrate the two superiority, it has concentrated function and so on step less control, batch control, logic sequential control, data acquisition.Basic component of DCSThe logic structure of the system needs realizing by the physics structure. We can sum up their physics structure as the structure of the type of a gleam of past three simply . first line refers to its skeleton computer network, the three means that join three kinds of different kinds of nodes in the network: Face on-the-spot I/O which is accused of the course scene to control and stand; Facing the attenbants operators station; Facing DCS supervise the administrative staffs engineer standing.I/O controls the station live An on-the-spot I / O is controlled and stood to finish dealing with and realizing the network node of digital control DDC (Direct Digital Control ) directly to on-the-spot I/O of course, there are three main functions: 1, which carried on digitization of various kinds of on-the-spot course amount (such as the flow , pressure ), and the quantity after digitizing is stored in the memory , form one keep the same with on-the-spot course amountly, can one-one is it video in real time according to actual running situation with newer on-the-spot course quantity to change in real timing; 2, the real-time data gathering our station are sent to operators station , standing and other engineers live through the network FO control the station, in order to realize the supervision and control of the whole system, at the same time it is stood the message issued by operators standing , engineer that can also receive , in order to realize that establishes artificial control or parameter to our station of the scene. 3, calculation and closing ring controlling , in order to control etc. IN realizing the part and automaticallying control in our station , return circuit , algorithm whose some classical algorithm generally, can remove theatrical makeup and costume non-standard algorithm , complicated algorithm. Operators station The operator of DCS deals with all functions of man-machine interface (MMI-Man Machine Interface ) related to operating and operating at station, embody in and offer the man-machine interface for operating attendants mainly, enable operators to understand on-the-spot operation state , to present value of various kinds of operation parameters , and have unusual situations to take place etc. In time through operators station, and can control and regulate the craft course through the input equipment , so as to ensure the security of the production process , reliable , high-efficient , high quality. It is colored CRT that operators main man-machine interface equipment of the station outputs the respect in the computer, which control the equipment for industry keyboard and cursor in importing in computer (such as the mouse, orbit ball). The content outputted on CRT includes mainly: 1, the simulation flow chart of the production process (namely by imitating production device and production line that the figure expresses), which wins a bid of real-time status with all key data ,to control parameter and equipment; 2, the warning window: By arranging the time order way (namely the most emerging alarm ranks the top of the window ) and listing the unusual situation appearing in production processes , if number value restricts . Reporting to the police should include time , unusual state and value , confirming by operator and unusual brief illustration to tabulate already of the unusual data to unusually appear ; 3, the real-time trend shows: With curve say come out change recently, producting process of data, so that the operator understands its development and change to some extent, and can help to analyse the running situation of the production process .which Can generally show the trend curves of 4-8 data in the same system of coordinates , so can compare with all relevant data ,to make the analysis on on-the-spot situation very more clearly. The engineer stands It is disposed to DCS off-line that the engineer stands, configuration and network node supervised , controlled , maintained online. Its main function is to finish the systematic configuration , dispose the work, and monitor the each nodal running situation when real when the line is operated, make system engineer can stand in time adjusting system disposing and some settlement of systematic parameter through engineer, to make the system in the best working state at any time. Systematic network It is all some isolated nodes that on-the-spot I/O is controlled and stands , stands at operators station and engineer, to finish ones own work each. If none of unified coordination can not form the intact system, the systematic network offers the foundation for coordinating , which becomes the core of the whole system. 1, Network characteristic Different from some network that general office automation adopts, the communication network that DCS adopts was used for the control and management of have the industrial production process, so, it should possess the characteristics of the following : Real-time character is good, respond fast dynamically Meet the abominable on-the-spot environment of industry Dependability is high Opening is good 2, Network structure Early LAN with better real-time character of often adopt IEEE802.4 making brand total network or IEEE802.5 to make the card surround the network alone etc. of information management network of DCS control system. But no matter domestic or abroad, which uses most is IEEE802.3 CSMA/CD Ethernet at present. Ethernet enters industry and comes from its low cost , opening , extensive development and support of using the software and hardware live, what it uses the most extensive network technology at present. The industrial control network adopts Ethernet, and can make the industrial control network incorporate the development mainstream of the network technology of the computer . DCS controller function block: DCS not only able to complete the functions of the original analog instruments, and much higher than analog instruments. This is because it uses advanced computer technology, communication technology, CRT technology and control technology 4C technology. Using digital control after the pre-deposited in the controller ROM of the algorithm is infinite, each representative of an algorithm kinds of functions. These features in the simulated instrument is achieved with analog circuits, which are analog line drift, resistors, capacitors and other devices restricted, as a high precision analog meter high cost, or even almost impossible. The digital control algorithm is implemented with the program. With a program to replace the analog line can realize the function. Theoretically infinite, this is great progress. The principle for the various DCS systems are the same. Algorithms are usually called functional blocks. Functional block called the function block library assembly.DCS controller mainly by the CPU, ROM, RAM, E2PROM, address setting switches and other components. CPU complete the operation, ROM is used to keep the operating system, function block libraries, function blocks are arranged in the ROM is set in, the user can not be changed. RAM is used to save CPU computational results and I / O signals. E2PROM keep even with the function block into the control program. Under the power, the control program is not lost. Moreover, the control scheme not suitable, you can modify. Modify the use of ultraviolet radiation, to erase the contents of the E2PROM. Controller in the network should be address by the address switches to set. Function blocks are arranged in the ROM in some DCS calls this arrangement for the function code. Code sequence is a functional block in the librarys address. Various manufacturers of DCS on the treatment of some differences in computing algorithms, so not the same name. If the internal DCS Instrument said the algorithms, but its essence is a process, essentially the same. In the use of these function blocks, it should indicate that the function block input and output relationship between the operation, there computing needs many parameters. According to the controlled object in the user to determine the control strategy formation control program, select the function block library with the required control function blocks, clear the connection between the relationship between functional blocks, and first of all define it in the E2PROM of the address, and other function blocks and links are expressed with the address. At the same time fill in the required parameters. The work of known configuration, which is different from the language used for programming. Configuration, can be used as maps, which means CAD. For a CAD software that can draw a control loop for each function block and the necessary connection between them. It is known as the engineer station. Use it to the controller configuration. Configuration, the first draw SAMA plan or ISA plan. The use of small function block, the painting SAMA diagram, large functional blocks, the picture ISA plan.1,Development course of PLC In the course of industrial production, a large number of switch amount orders are controlled, it carries on order movements according to the logic condition , and carry on the control that the chain protected movements according to the logic relation, and the data of a large number of dispersed quantity are gathered . Traditionally, these functions were realized through the pneumatic or electric control system. The Company put forward and replaced the demand which continued the electric control device in U.S.A. GM in 1968 (General Motors ), in second year, American digital company develops the control device based on integrated circuit and electronic technology, adopt means of procedure apply electric to control for the first time, this it is first generation that can programme the controller , call Programmable Controller (PC ). After the personal computer ( abbreviated as PC ) develops, for being convenient, in order to reflect the function characteristic of the programmable controller too, can programme controller name Programmable Logic Controller (PLC).The eighties of last century is to the middle period of the 1990s, it was PLC the period with the fastest developing speed, the annual growth kept 300%. This period, PLC is improved by a large margin in power to dispose of analog quantity , digital operation ability , man-machine interface ability and network ability , PLC enters the course controlled field gradually, has replaced and in DCS system ruling position on the course controlled field in some is used. PLC have commonability to be strong easy to use meeting surface wide , dependability high , anti-interference ability strong , programming characteristicking such as being simple. The position in PLC is controlled in the industrial automation especially the order is controlled, in foreseeable future, can replace. 1.2 Composition of PLC Divide from structure, PLC is divided into a regular type and sectional (module type ) two kindsRegular type PLC including CPU board , I/O board , showing the panel , memory lump , power ,etc., these elements are made up into a whole not detachable . Module type PLC includes CPU module , I/O module , memory , power module , the baseplate or the framework, the module can be made up and disposes according to certain rule. 1.3 Composition of CPU CPU is a core of PLC, functions as nerve center, each set of PLC has one CPU at least, it receives and stores users procedure and data according to the function that the systematic procedure of PLC gives, gathered and input the state or data that the device sends here live by means of scanning, deposit register that stipulate , meanwhile , diagnose power and working state and grammar mistake ,etc. , programming of course of circuit inside the PLC. Enter after running, read the order one by one from users procedure storing device , produce the corresponding control signal according to the task that the order stipulates after analysing, go to command relevant control circuits . CPU and realizes by arithmetic unit , controller , register mainly the data , control and state bus of the connection among them are formed , unit CPU still includes peripheral chip , interface of the bus and relevant circuit. The memory is used for storing the procedure and data mainly, is indispensable composition unit PLC. In users view , it is unnecessary to analyse the inside circuit of CPU in detail, but there should be enough understanding to the working mechnism of every part. The controller of CPU controls CPU and works, is read the order, explained the order and executed instruction by it. But working rhythm is controlled from the signal of shaking . The arithmetic unit is used for carrying on figures or logic operation, work under the circumstances that the controller is commanded. The register is participated in operation, store the middle result of operation, it works under the circumstances that the controller is commanded too. CPU speed and capacity of memory are important parameters of PLC, they are determining the working speed of PLC, IO quantity and capacity of software,etc., so is exercising restraint in controlling the scale . 1.4 I/O moduleThe interface of PLC and electric return circuit , finished through inputting the output (I/O ). I/O circuit of I/O module integrated PLC, it is input temporarily the storing device reflects the state of the input signal, export and click and reflect that exports the state of the latch. Input module vary electric signal digital signal enter PLC system , output module to be opposite. I/O is divided and imported (DI) for the switch amount, the switch amount is exported (DO), analog quantity is input (AI), analog quantity is exported (AO),etc. the module . Commonly used I/O is classified as follows: Switch amount: Divide according to the voltage level, there are 220VAC , 110VAC , 24VDC , divide according to the way of isolating, there are relays that are isolated and isolated with the transistor. Analog quantity: Divide according to the signal type, the electric current type (4-20mA , 0-20mA ) , voltage having type (0-10V, 0-5V,- 10-10V),etc.,it is according to precision fen, there is 12bit , 14bit, 16bit ,etc. Besides above-mentioned IO in common use , there is special IO module , for instance such module as thermal resistance , electric thermocouple , pulse ,etc. Is it confirm module specification and quantity to count according to I/O, I/O module but many and very little, its great number receive CPU can basic ability of disposition of management most, namely is counted the restriction by the biggest baseplate or the framework trough . 1.5 Power module PLC power is used for offering the working power for integrated circuit of every module of PLC. Meanwhile, some still offer the working power of 24V for inputting the circuit. The type is as follows, that the power imports Exchange the power (220VAC or 110VAC ), direct current power (a commonly used one is 24VDC). 1.6 The baseplate or the frameworkMost module type PLCs use the baseplate or the framework, its function is: Have electrically, realize the connection among every module , enable CPU to visit all module on the baseplate, on machinery , realize the connection among every module , make every module form a whole . 1.7 Other equipment of PLC system 1. 7.A programming equipment: The programmable device is that PLC develops and adopts, monitors operating, checks and maintains the indispensable device, used in programming , do some settlement , working state controlling the system that PLC and PLC control to the system, but it does not participate in directly and control and run live . The small programmable device PLC generally has holding type programmable device, generally the computer (operates the programming software ) makes programmable device at present. That is to say we system go to location plane. 1.7.B Man-machine interface: The simplest man-machine interface is indicator lamp and button, the liquid crystal reject (or the touch-sensitive screen ) an organic whole type operators terminal station of the type and use more and more extensive at present, it is popularized very much that the computer (operation configuration software ) makes man-machine interface.1.8 The communication of PLC is networked May collect , convey producing and manage the data promptly and efficiently while relying on the advanced industrial network technology. So, the importance of the network in the automatic system integration project is more and more remarkable, even someone proposes the view statement that the network is the controller .PLC have function that communication network, it make PLC and between the PLC , PLC with go to location computer and other intellectual equipment can exchange information , form a unified whole, realize dispersing centralized control. Most PLC has RS-232 interface, puts and s