【正文】 無(wú) 錫 職 業(yè) 技 術(shù) 學(xué) 院 畢業(yè)設(shè)計(jì)說(shuō)明書(shū)（英文翻譯） 1 英 文 PLC development and market conditions PLC development history Programmable Logic Controller’s English name is Programmable Controller。 in the 20th century 7080 age continuously abbreviation is PC. As a result of to the 9039。s, the personal puter develops, also the abbreviation is PC。 Adds scope which the programmable foreword concept covers too in a big way, therefore American AB Corporation chooses a name for the first time the programmable foreword controller as the programmable foreword logic controller (PLCProgrammable Logic Controller), in order to be convenient, still was called PLC was the programmable foreword controller. Some people the system which pose the programmable foreword controller are called the PCS programmable foreword control system, emphasized the programmable foreword controller production merchant provided to the people already is plete is systematic. In 1968 American GM (general automobile) the pany proposed the substitution blackwhite control installment request, the second year American numeral pany developed the first generation of programmable foreword controller, has satisfied the GM Corporation assembly line request. Along with the integrated circuit technology and the puter technology development, now had the fifth generation of PLC product. In take changes the geometry shape and the machine capability transforms as the characteristic manufacture industry and take the physical change and the chemical change the raw material the product as in the characteristic process industry, besides by the continual quantity primarily reaction control, has specially had the massive switches quantity primarily splitring sequential control in the manufacture industry, it carries on the smooth movement number according to the logical condition according to the succession movement。； Moreover also has with the order, the succession has nothing to do with carries on the chainlike protection movement according to the logical relations the control。 As well as the massive switches quantity, the arteries impulse, the time, the counter, the simulation quantity reports to the police and so on the condition quantity primarily data acquisition surveillance. As a result of these controls and surveillance request, therefore PLC developed the substitution relay line and carries on the sequential control primarily product. In many years production practice, has gradually formed PLC, DCS and the IPC tripod sets up the potential, like table 1, but also has other single return route intelligence type regulators and so on to account for the certain percentage in the market. In the 8039。s to 9039。s intermediate stages, is PLC develops the quickest time, the yearly rate continuously maintenance is 30~40%. As a result of the PLC machine relation processing simulation ability and the work aspect function progress, has occupied a part of DCS market (process control) and has gradually monopolized profession and so on sewage treatment, but as a result of industry PC (IPC) the appearance, specially in recent years the field bus technology development, IPC and FCS have also occupied a part of PLC market, therefore the recent years PLC rate of rise, always saying was gradually slow. At present the world has more than 200 factories to produce more than 300 varieties PLC product, main application in automobile (23%), grain processing (%), chemistry/drugs manufacture (%), metal/mine (%), paper pulp/papermaking (%) and so on profession . PLC market conditions Domestic PLC production factory approximately 30, but has not formed quite has the scale the productivity and the famous brand goods, but also some part is by imitates, the document received assembly or pastes the sign the way production, therefore may say PLC has not formed the manufacture industry in our country. As the principle, the technology and the craft do not have the most advanced technique difficulty the product, so long as diligently, is can form the manufacture industry. 無(wú) 錫 職 業(yè) 技 術(shù) 學(xué) 院 畢業(yè)設(shè)計(jì)說(shuō)明書(shū)（英文翻譯） 2 In the PLC application aspect, our country is very active, in recent years every year approximately newly invested 100,000 to wrap the PLC product, the year sales volume 3 billion Yuan, and the application profession very is also broad. But pares with other countries, in machinefinishing and production line aspect application, but also needs to enlarge the investment. The PLC market potential is huge, not only in our country, even if also has the investigation in industry developed Japan to indicate, the PLC necessary integration of machinery product proportion accounts for 42%, used the relay, the contact device control still has 24%. Therefore, needs to apply PLC the situation very to be also many, in our country was so. Looked from the technical innovation angle that, the our country large and middle scale enterprises also must vigorously develop CIMS (puter integration manufacture system), must form the FMS flexibility manufacture system in the mechanical factory, PLC is a foundation, therefore the PLC market is broad. PLC has reliable, the price small advantage, the function stably plete, the application nimble is convenient, the operation maintenance convenient merit, this is it can lasting hold