DZ199PLC在啤酒灌裝壓蓋機(jī)和啤酒貼標(biāo)機(jī)上的應(yīng)用

DZ199PLC在啤酒灌裝壓蓋機(jī)和啤酒貼標(biāo)機(jī)上的應(yīng)用,dz199plc,啤酒,灌裝,壓蓋,以及,貼標(biāo)機(jī)上,應(yīng)用,利用,運(yùn)用 外文資料-- 44 --國(guó)外PLC發(fā)展綜述重慶工業(yè)自動(dòng)化儀表研究所 趙有潔 摘要：主要介紹國(guó)外可編程控制器市場(chǎng)及其過(guò)程控制應(yīng)用發(fā)展情況。在過(guò)去一些年中，PLC發(fā)展很快，產(chǎn)品的功能和結(jié)構(gòu)不斷改進(jìn)，應(yīng)用范圍迅速擴(kuò)展，從原來(lái)的順序邏輯控制發(fā)展到連續(xù)和分批過(guò)程控制。隨著技術(shù)發(fā)展，功能更強(qiáng)的PLC系統(tǒng)已經(jīng)與其它控制系統(tǒng)，如工業(yè)控制微型機(jī)、分散型控制系統(tǒng)(DCS)等，在功能范圍的應(yīng)用方面相互滲透，甚至相互融合。在許多場(chǎng)合下，人們很難分清哪些是、哪些不是PLC系統(tǒng)。PLC實(shí)際上已經(jīng)成為一種通用的微處理機(jī)控制器，廣泛用于工業(yè)和過(guò)程控制。分批過(guò)程控制既需要順序控制，也需要調(diào)節(jié)控制。這種部分采用順控、部分采用連續(xù)模擬控制的應(yīng)用任務(wù)最適合采用PLC系統(tǒng)進(jìn)行經(jīng)濟(jì)、合算的控制。 PLC市場(chǎng)PLC市場(chǎng)這些年來(lái)涌現(xiàn)出很多新的廠家，每年出現(xiàn)數(shù)10種新的產(chǎn)品，其中有功能全、處理能力強(qiáng)、以各種形式結(jié)合模擬I/O和門(mén)PID回路控制的、具有優(yōu)良批量處理特性的高檔產(chǎn)品，也有價(jià)格低廉、價(jià)格性能比好、應(yīng)用廣泛的低檔產(chǎn)品。新一代的分散型控制系統(tǒng)包括分批控制和邏輯組件，其中有的利用同一個(gè)機(jī)箱把連續(xù)控制和PLC邏輯功能結(jié)合起來(lái)，不必采用單獨(dú)的PLC。據(jù)美刊《Contro1Eng》的不完全統(tǒng)計(jì),在1983—1988年期間，PLC產(chǎn)品數(shù)量成倍增長(zhǎng)，從1983年37個(gè)廠家、100種產(chǎn)品型號(hào)，增加到70個(gè)廠家，300多種產(chǎn)品型號(hào)。從1988年開(kāi)始，國(guó)外有人預(yù)測(cè)，PLC經(jīng)過(guò)幾年高速發(fā)展之后，今后可能放慢增長(zhǎng)速度。在分批控制這部分市場(chǎng)上，從前PLC銷售額增長(zhǎng)率大于DCS的狀態(tài)可能會(huì)倒過(guò)來(lái)，預(yù)計(jì)DCS銷售額增長(zhǎng)速度將加快并超過(guò)PLC。但從總體來(lái)看，PLC將保持增長(zhǎng)勢(shì)頭。根據(jù)美國(guó)從事市場(chǎng)分析的VD公司最近報(bào)告,預(yù)計(jì)美國(guó)市場(chǎng)PLC銷售額在1989年接近9億美元。平均年增長(zhǎng)率達(dá)9.3％，小型PLC大于大型PLC的年平均增長(zhǎng)率。小型PLC銷售量增長(zhǎng)較快的一個(gè)原因，是其價(jià)格性能比的改進(jìn)較快。有的保持原有的功能、降低了成本，有的保持原來(lái)的成本和規(guī)模、增強(qiáng)了功能。市場(chǎng)的成熟和競(jìng)爭(zhēng)，迫使PLC廠家不斷改進(jìn)產(chǎn)品以求生存和發(fā)展。過(guò)程控制中的PLC從80年代初開(kāi)始，就有一些化工、醫(yī)藥、石油和天然氣公司開(kāi)始把PLC系統(tǒng)用于過(guò)程控制任務(wù)。隨著微處理機(jī)和軟件技術(shù)的發(fā)展、操作員接口的使用、PLC網(wǎng)絡(luò)的開(kāi)發(fā),人們甚至把PLC視為以低成本實(shí)現(xiàn)分散控制的一種技術(shù)。DCS廠家也開(kāi)始用插入式分批控制器和對(duì)PLC系遼寧工程技術(shù)大學(xué)畢業(yè)設(shè)計(jì)（論文）-- 45 --統(tǒng)的連接設(shè)備補(bǔ)充原來(lái)的DCS。在某些應(yīng)用中，PLC廠家提供的硬件和軟件已足以使他們的產(chǎn)品或系統(tǒng)與DCS廠家的進(jìn)行競(jìng)爭(zhēng)。 1．技術(shù)發(fā)展促進(jìn)PLC的發(fā)展 硬件、軟件技術(shù)在過(guò)去幾年中的進(jìn)展，改善了PLC的編程特性，使它們的效率、存貯器容量相速度提高3—5倍。對(duì)于過(guò)程控制用的PLC，除了常規(guī)模擬輸入外，還新開(kāi)發(fā)了高速模擬輸入，獨(dú)立PID控制器、熱電偶、RTD以及其它類似的模件。這些改進(jìn)使數(shù)字與模擬技術(shù)的差異進(jìn)一步縮小，使PLC系統(tǒng)比從前更加方便適用。帶監(jiān)控計(jì)算機(jī)的操作員接口的使用，把PLC引入了控制室。各種監(jiān)控計(jì)算機(jī)，包括個(gè)人計(jì)算機(jī)(PC)、工作站、小型機(jī)都變得更加高速、有效、合算。這些監(jiān)控計(jì)算機(jī)與新的標(biāo)準(zhǔn)接口組件和PLC網(wǎng)絡(luò)相結(jié)合，能夠提供屏幕顯示、數(shù)據(jù)采集、記錄保持、回路面板等功能。它們就相當(dāng)于分散型控制系統(tǒng)具有的功能。 PID之類的智能I/O模件在近年中迅速發(fā)展起來(lái)。它們有效地?cái)U(kuò)展了控制系統(tǒng)功能，并有助于某些控制功能的分散。今天，PLC控制系統(tǒng)設(shè)計(jì)人員能把很多小型PLC組合在一個(gè)采用“同層通信”的高速控制鏈路上，并連接到PLC主機(jī)。PLC主機(jī)還可以連接到信息網(wǎng)絡(luò)。新的通信產(chǎn)品增加了PLC聯(lián)網(wǎng)能力，MAP標(biāo)準(zhǔn)取得了重大進(jìn)展，不同廠家的設(shè)備兼容性增加，人們可以對(duì)多個(gè)廠家的設(shè)備進(jìn)行選擇。 所有這些進(jìn)展，使PLC系統(tǒng)的處理能力和速度得到了重大改進(jìn)，能夠適合多種過(guò)程控制應(yīng)用。PLC本身雖然沒(méi)有DCS那樣可觀的計(jì)算和監(jiān)控功能，但是各種聞?dòng)赑LC的專用過(guò)程控制功能塊、專用模擬I/O塊、語(yǔ)言協(xié)處理機(jī)等，卻可以提供很多應(yīng)用任務(wù)必需的功能。高速模擬I/O、智能I/O和分散型PLC網(wǎng)絡(luò)的發(fā)展，正在使PLC系統(tǒng)的處理速度不斷增加。更快的網(wǎng)絡(luò)和計(jì)算機(jī)將會(huì)提高操作員接口的速度。 新的分散型PLC系統(tǒng)可以用一個(gè)PLC進(jìn)行分批處理，用另一個(gè)進(jìn)行連續(xù)處理，用第三個(gè)PLC進(jìn)行其它處理。所有這三個(gè)都連接到大型PLC主機(jī)。主機(jī)的任務(wù)是使整個(gè)系統(tǒng)協(xié)調(diào)操作。這樣的系統(tǒng)已在過(guò)程控制中廣泛應(yīng)用。 2．用軟件和硬件實(shí)現(xiàn)調(diào)節(jié)控制功能 采用PLC實(shí)現(xiàn)PID控制有兩種方法，一種是采用軟件功能，另一種是采用輔助硬件。用軟件實(shí)現(xiàn)的PID回路可以作為繼電器梯形圖范圍內(nèi)的功能塊，也可以作為單獨(dú)的功能。輔助硬件方法使回路編程對(duì)用戶更方便。除了標(biāo)準(zhǔn)PID控制功能，前饋、偏差控制、偏差報(bào)警及輸出限幅等，都可以用控制回路實(shí)現(xiàn)。 外文資料-- 46 --用軟件方法實(shí)現(xiàn)PID回路控制通常比用輔助硬件實(shí)現(xiàn)更經(jīng)濟(jì)合算。但是如果要求單回路的完整性，就須采用硬件方法。硬件PID控制器既可以是專用I/O模件，也可以是通過(guò)串行鏈路與PLC通信的獨(dú)立控制器。標(biāo)準(zhǔn)單回路控制器能非常靈活地用來(lái)解決分批控制問(wèn)題，而且還能與其它不采用PLC控制的設(shè)備兼容。 自適應(yīng)、自整定控制與PLC配合起來(lái)使用，可以減少試車(chē)時(shí)間、提高控制精度。AB公司研制的、以Foxboro。EXACT技術(shù)為基礎(chǔ)的回路按制器，以及Satt Control公司的ECA40自整定控制器(能與該公司的PLC系統(tǒng)通信)，是自整定控制器與PLC相結(jié)合的兩個(gè)例子?，F(xiàn)在有人預(yù)言，不久的將來(lái)，可以把自適應(yīng)整定功能變成PLC內(nèi)部的一種軟件。 3．過(guò)程控制PLC的優(yōu)點(diǎn)（1）靈活性：PLC是通用設(shè)備，一般通過(guò)編程而適用于過(guò)程控制。PLC系統(tǒng)允許使用專用產(chǎn)品。編程之后，用戶也容易修改程序。 系統(tǒng)工程師常用操作員接口軟件建立標(biāo)準(zhǔn)PLC過(guò)程控制回路和顯示屏。這種方法縮短了編程時(shí)間，使用起來(lái)很靈活。標(biāo)準(zhǔn)程序庫(kù)中包括比率/串級(jí)控制、單回路控制、線性化等功能，利用編程工具(與字處理機(jī)類似)的剪輯功能可將它們插進(jìn)PLC程序。標(biāo)準(zhǔn)操作員接口部件提供回路、分組、總貌顯示，以及報(bào)警和趨勢(shì)顯示。 (2)可維護(hù)性好：PLC一般由電氣技術(shù)人員維護(hù)，而計(jì)算機(jī)需要由工程師和程序員維護(hù)。很多工廠投有計(jì)算機(jī)維護(hù)人員，采用PLC比較容易維護(hù)。 (3)結(jié)實(shí)耐用、可靠他高：PLC能耐受惡劣的工業(yè)環(huán)境，不需要裝在有空調(diào)的環(huán)境中。用電池作后備的存貯器用于數(shù)據(jù)存貯， 對(duì)冗余CPU和I/O電纜連接采用熱后備組態(tài)。 (4)連接性：PLC具有優(yōu)良的連接性，能與各種外部設(shè)備通信。它有各種端口專用于第三方設(shè)備。這些端口為控制系統(tǒng)的信息輸入輸出提供通路。連接任務(wù)可由電氣技術(shù)人員完成。 (5)費(fèi)用低、經(jīng)濟(jì)上合算。 (6)其它優(yōu)點(diǎn)包括遠(yuǎn)程I/O、軟件庫(kù)的使用等。PC與PLCPLC的基本特長(zhǎng)是適合實(shí)際生產(chǎn)現(xiàn)場(chǎng)的控制，而PC(個(gè)人計(jì)算機(jī))通過(guò)訪問(wèn)PLC數(shù)據(jù)庫(kù)可以增強(qiáng)它在數(shù)據(jù)采集和分析方面的基本功能。因此人們?cè)敢獍裀C和PLC結(jié)合起來(lái)，構(gòu)成控制系統(tǒng)。當(dāng)前實(shí)現(xiàn)PC和PLC相結(jié)合主要有三種方法：1）增加通信、聯(lián)網(wǎng)能力；2）采用加固型的工業(yè)PC；遼寧工程技術(shù)大學(xué)畢業(yè)設(shè)計(jì)（論文）-- 47 --3）研制把計(jì)算機(jī)總線連接到專用I/O的接口硬件。 除了開(kāi)發(fā)比較高級(jí)的工業(yè)LAN、支持MAP標(biāo)準(zhǔn)通信而外，PLC廠家也很重視PC/PLC網(wǎng)絡(luò)的發(fā)展；PC/PLC網(wǎng)絡(luò)費(fèi)用低、用途廣，深受小型工廠用戶歡迎，用于數(shù)據(jù)采集等功能已經(jīng)顯示出很大優(yōu)越性。據(jù)美國(guó)Omron電子公司的Morrow估計(jì)，在1988年內(nèi)建立的PC/PLC網(wǎng)絡(luò)約有15000個(gè)。 目前，PC在工業(yè)控制中通常用作編程器或人/機(jī)接口。如果用于控制功能，就需添加輔助硬件或采用合適的軟件。發(fā)展工業(yè)PC的一種方式是采用協(xié)處理機(jī)模板處理實(shí)時(shí)任務(wù)。有的廠家正在考慮把PLC作為一種插扳，插進(jìn)PC，使PLC在控制系統(tǒng)中充當(dāng)一種實(shí)時(shí)控制模件。 PLC計(jì)算機(jī)化、大型PLC具備PC功能，是今天PLC技術(shù)發(fā)展的一種趨勢(shì)。與老的PLC相比，新的PLC采用功能強(qiáng)大的微處理機(jī)，有數(shù)學(xué)功能和大容量存貯器，與PC機(jī)甚至小型計(jì)算機(jī)有較多的相同點(diǎn)。一些大型、高功能PLC現(xiàn)在遠(yuǎn)遠(yuǎn)不止有繼電器或其它邏輯功能，已能把數(shù)學(xué)和連續(xù)控制功能與通信結(jié)合起來(lái)，PLC可以連接上位機(jī)，也可以與同一級(jí)PLC通信。當(dāng)然這只是高檔或中、大型PLC的一種趨向。在廣泛的OEM應(yīng)用中，仍然需要獨(dú)立的PLC。 PC與PLC相結(jié)合的分批過(guò)程控制系統(tǒng)，在過(guò)去幾年中十分引入注目。這種分批控制系統(tǒng)適應(yīng)化工、醫(yī)藥、食品、輕工等生產(chǎn)過(guò)程實(shí)現(xiàn)多品種、小批量生產(chǎn)的需要，有利于簡(jiǎn)化生產(chǎn)操作和穩(wěn)定質(zhì)量，有較高的靈活性和較好的價(jià)格性能比。目前這類系統(tǒng)一股仍用PC作操作站、編程器、工作終端，PLC起著控制對(duì)象輸入、輸出接口的作用。在有的情況下，也用PC完成PLC的任務(wù)。很多專業(yè)PLC廠家都注意發(fā)展在PC機(jī)上運(yùn)行的各種軟件包，與此同時(shí)，也都采用前端或I/0擴(kuò)展。 Foreign PLC develops the survey外文資料-- 48 --Industrial automation instrument research institute of Chongqing Zhao is cleanSummary : Programmable controller market and his course control and use the development to make the introduction to foreign countries.In year a little in the past, PLC develop quickly, function and structure of products update, the range of application is expanded rapidly, grow from original order logic control to in succession and the course is controlled in turn. With the technical development, FLC system with better function, with other control systems, for instance industrial control microcomputer , control system (DCS ) ,etc of dispersing etc， range accumulate application permeate each other in function, even merge each other. Under a lot of occasion , very difficult to tell which be people have, which PLC system. PLC become one in common use microprocessor controller already in fact, used in industry and course control extensively. The course is controlled to need the order to control in turn, need regulating and controlling too. This kind adopt suitable to accuse of , adopt application task controlled to imitate is it adopt PLC system carry on economic , worthwhile control to suitable for most in succession partly partly.PLC marketPLC market a lot of new producers emerge in these years , appear several 10 new product every year, among them there is the whole function, deal with ability strong , combine simulation I/O and , with fine batch processing characteristic top-grade product that return circuit control , PID of door , in various forms, there is cheap , price performance than the good , uses and extensive low- grade products too. The scattered control system of new generation includes control and logic package in turn , the ones that have conbine controlling in succession and PLC logic function together with the same machine case among them, needn't adopt single PLC . According to American incomplete statistics of publication" Contro1Eng ", during 1983-1988, PLC product quantity double and redouble, 37 producers , 100 kinds of products types , 遼寧工程技術(shù)大學(xué)畢業(yè)設(shè)計(jì)（論文）-- 49 --rose to 70 producers, more than 300 kinds of products types since 1983. Since 1988, foreign someone predict through how long is PLC after developing at a high speed, may slow down the growth rate in the future. At control the market in turn, PLC sales amount rate of increase greater than state of DCS may be turned around in the past, it is estimated that DCS sales amount growth rate will accelerate and exceed PLC. But take it as a whole, PLC will keep the growth. Used in the industry and course to control extensively through becoming a kind of microprocessor controller in common use . The course is controlled to need the order to control in turn, need regulating and controlling too. This kind adopt suitable to accuse of , adopt application task controlled to imitate is it adopt PLC system carry on economic , worthwhile control to suitable for most in succession partly partly.Have reported recently according to VD Company (Ven-ture Development Co ) that U.S.A. is engaged in market analysis, it is estimated that American market FLC sales amount is close to 900 million dollars within 1989. The average annual growth 9.3%, small-scale PLC is greater than the average annual rate of increase of large-scale PLC.It is small-scale PLC sales volume last very fast pieces of reason,not for its price of performances than have very more fast improvement. Some have kept the already existing function, reduction of cost , some have kept original cost and scale, strengthened the function. Maturity and competition of the market, force PLC producer to update the products in order to seek survival and develop.PLC in the course is controlledSince the beginning of the eighties, some chemical industry, medicine, petroleum, natural gas company is it control the task PLC system for course to begin. Use of the with the development of the microprocessor and software engineering , operator interface , development of PLC network, people even regard PLC as with the low cost and realize dispersing a kind of technology controlled. DCS producer is it spend bayonet controller and to PLC connection 外文資料-- 50 --equipment supplementary original DCS of system in turn to begin too. In some being in using, PLC hardware and already enough to make products or system of them compete with DC5 producer software that producer offer. 1.The technical development promotes the development of PLC.1.The technical development promotes the development of PLCHardware, progress in the past several years of software engineering, have improved the programming characteristic of PLC, make efficiency of them , person who store capacity phase speed raise by 3-5 times. As to PLC that course is it spend to control , except importing in routine simulation , develop at a high speed simulation input newly, independent PID controller, electric thermocouple, RTD and other similar mould one. Improvement the make figure and simulation difference of technology dwindle further , make PLC to be system further more convenient to be suitable than in the past. Is it control operator use of interface of computer to take , lead PLC into the control room. Various kinds of control the computer, including the personal computer (PC ), work station , minicomputer all become more high-speed , more effective , more worthwhile. These control the computer to combine with new standard interface package and PLC network, function of can offer the display , data to gather , writing down keeping , return circuit panel ing etc.. They are equivalent to the function that the dispersing type control system have. Intellectual I/O mould one of PID ,etc. is developed rapidly in recent years. They have expanded the function of the control system effectively, and contribute to some scattering of controlling the function. Today, control system designers of PLC can make a lot of small-scale PLCs up on a chain of controlling at a high speed adopted " with one layer of communication , and connect to PLC host computer . PLC host computer can also be connected to the information network. The new communication products have increased PLC and networked ability , MAP standard has made great progress, the compatible increase of equipment of different producers, people can choose the equipment of a lot of producers . 遼寧工程技術(shù)大學(xué)畢業(yè)設(shè)計(jì)（論文）-- 51 --All these progress, make treatment ability and tempo of PLC system improved greatly, can be suitable for many kinds of course and control application. PLC has no so considerable calculation of DCS and control function, but various kinds of hear special-purpose course in PLC control functional block , special-purpose lump , language association processor ,etc. , I/O of simulation ,, but can offer a lot functions of using letting and must be needed . High-speed simulation I/O, intellectual I/O and PLC development of network of dispersing etc., make PLC processing speeds of system increase constantly. Quick network improve operator speed of interface compared with calculation. New scattered PLC system can divide batch processing by one PLC , deals with another one in succession , carry on other treatment by third PLC. All these three are connected to large-scale PLC host computer . The task of the host computer is to make the whole system coordinate and operate. Such a system has been already the extensive application in the course is controlled.2.Realize regulating and controlling the function with the software and hardware. Adopt PLC to realize that PID controls two kinds of methods , one adopts the function of the software , another kind adopts the auxiliary hardware. Can be regarded as the functional block in the ladder- shaped picture range of relay with the PID return circuit that the software realizes, can be regarded as the single function too. The auxiliary hardware method makes return circuit programming more convenient to users. Except standard PID controls the function, the feedforward , deviation are controlled, the deviation reports to the police and exports amplitude limiting etc, can realize by controlling the return circuit .Realize with software method PID return circuit control usually than realize with auxiliary hardware economical. But if require the integrality of the single return circuit , must adopt the method of the hardware . The hardware PID controller can be special-purpose I/O mould one, can pass the serial chain and independent controller of PLC communication too. The standard form return 外文資料-- 52 --circuit controller can be used for solving the control problem in turn very flexibly , still can adopt with other equipment that PLC control compatible.Self-adaptation,, whole to is it is it is it use to stand up to cooperate with PLC to control definitely since, can reduce the time of taking a trial run , raise the precision of controlling . What AB Company develops, with Foxboro. EXACT return circuit of technology according to person who make, and Satt Control ECA40 of Company make controller(can with systematic communication of PLC of Company this) exactly since, whole two examples that the controller combines with PLC definitely since. Someone prophesies now , in near future, can turn the whole definitely function of the self-adaptation into a kind of software within PLC .3.The course controls the advantage of PLC(1)Flexibility : PLC is the equipment in common use , generally suitable for the course to control through programming. PLC system allows to use the special-purpose products. After programming, users are apt to revise the procedure too. System engineer daily operator interface software of Hua Bao set up standard PLC course control the return circuit and display screen. This kind of method has shortenned programming time, it is very flexible to use. Including the the rate / the functions , such as bunches of control , single return circuit controlling , linearization ,etc. in the standardization program storehouse, the film editing function of utilizing the programming tool (similar to word processor ) can inject them PLC procedure . Standard operator interface root one offer the return circuit , divide into groups, the total looks shows, and report to the police and show with the trend. (2)The maintainability is good: PLC is generally safeguarded by the electric technical staff, and the computer needs maintaining by the engineer and programmer. A lot of factory throw have computer attenbant, easy to maintain to adopt PLC. (3)Durable and durable , reliable he is tall: PLC ability receive abominable 遼寧工程技術(shù)大學(xué)畢業(yè)設(shè)計(jì)（論文）-- 53 --industrial environment , is it put among environment to have the air conditioner to need. Make with battery reserve person who store store for data , adopt hot reserve configuration to redundant CPU and I/O cable connection.(4)Joining : PLC has fine connections, can be with various kinds of outside equipment communication. It has various kinds of ports special-purpose in third party's equipment. These ports offer the thorough fare for importing and exporting in information of the control system. The connecting the task can be finished by electric technical staff. (5)The expenses are low, economically worthwhile. (6) Other advantages include use of distant place I/O .PC and of PLCs.specialty not basic of PLC to suit control of production scene not actual of, and PC (personal computer) through visit PLC database can strengthen it gather and analyse basic function of in data. So people would like to combine PC with PLC, form the control system. Realize at present that PC combines with PLC there are three kinds of methods mainly:1) Increase communication , network ability ;2)Adopt industry PC of the strengthening type; 3)Is it connect special-purpose interface hardware of I/O to computer bus to develop.Except develop advanced industry LAN , support MAP standard communication , PLC producer pay attention to PC/PLC development of network very much too; PC/PLC network expenses low, use wide, welcome deeply by small-scale factory user , used in data person who gather function demonstrate heavy superiority very already. According to the estimation by Morrow of U.S.A. Omron electronics corporation, nearly there are 15000 PC/PLC networks set up within 1988.At present, PC is usually used as programmable device or the people / the interface of the machine in industrial control. Used for controlling the 外文資料-- 54 --function , need to add the auxiliary hardware or adopt the suitable software. A way to develop industry PC is to adopt the processor template of the association to deal with the real-time task. Some producer regard PLC as one is it pull to insert , inject PC , make PLC make first real-time control mould one among control system consideration. PLC computerization , large-scale PLC possess PC function, today PLC a kind of trend of technical development. Compared with old PLC, new PLC adopts the powerful microprocessor, is mathematics function and large capacity storing device , have more common characteristics with the PC even minicom. Some large-scale , high function PLCs are far above having the relay or other logic functions far now, can control mathematics function combine with communicating , PLC can connect location plane to in succession already, can be with communicating with first class PLC too. Certainly this is only a kind of trend of top-grade or medium-and-large-sized PLC. In extensive OEM is used , still need independent PLC. The control system of the course in turn that PC combined with PLC, introduced and fixed one's eyes on very much in the past several years. This kind control system meet chemical industry , medicine , food , light industry production process realize many variety , little need that produces in batches in turn, help to simplify production operation and stabilize quality, there is higher flexibility that compares with better price performance . The system one at present do exercises and act as standing, programmable device , work terminal station with PC still, PLC plays a role in controlling the target and inputting, exporting interface . In case of having , finish the task of PLC with PC too. A lot of professional PLC producers all pay attention to developing various kinds of software package operated on the PC meanwhile , adopt the front or I/0 to expand too.