【正文】 使用它們的方法相對(duì)來說比較簡(jiǎn)單，包括大型的順序和動(dòng)作控制，大型的設(shè)備通過使用比較。它還包括農(nóng)場(chǎng)和施工設(shè)備的制造，內(nèi)燃機(jī)和發(fā)動(dòng)機(jī)的制造，機(jī)械工具的制造，以及特殊制造行業(yè)如煙草業(yè)、鞋業(yè)、電梯和塑模行業(yè)等?？刂破鹘?jīng)常被用于順序和動(dòng)作控制，以及被用于完成精密的材料選取工作③非電類器械。金屬制造部分是由許多輔助部分和過程組成的，其中大部分是金屬鑄，以及一小部分的金屬切割。但是一向用于鐵道工業(yè)的創(chuàng)新應(yīng)用是：采用可編程序控制器作為信號(hào)跟蹤和開關(guān)控制單元，可通過電話或微波環(huán)節(jié)遠(yuǎn)程操作及與中心發(fā)送站進(jìn)行通訊。在這兒，對(duì)于工廠數(shù)據(jù)的采集的數(shù)據(jù)包括外部貴重金屬，對(duì)設(shè)計(jì)完善性很重要的工序，或是要求的調(diào)整機(jī)構(gòu)的資料。飛機(jī)及宇宙飛船部分采用可編程序控制器主要用于金屬的切割與鑄造。它們中的大部分用于結(jié)合了發(fā)展中的數(shù)據(jù)管理與通訊的順序及指示控制。可編程序控制器被廣泛的應(yīng)用于上述行業(yè)，特別是自動(dòng)化。這種結(jié)構(gòu)一般分為兩大類：一種是單獨(dú)的制造工業(yè)和立體中存在一些輔助部分（或是子系統(tǒng)）的行業(yè)（1）單獨(dú)的制造工業(yè)。一些簡(jiǎn)單且技術(shù)較低的系統(tǒng)如果用來操作根本不可能完成或非常難得工作將造成很大的損失?，F(xiàn)在，我們將學(xué)習(xí)通用種類的可編程控制器的應(yīng)用，主要了解以下幾部分：為了典型應(yīng)用而如向象操作一個(gè)系統(tǒng)，當(dāng)今普遍應(yīng)用中的一些邏輯組合，包括基礎(chǔ)的，工業(yè)專用的以及普遍。事實(shí)上，通過它創(chuàng)新的應(yīng)用，如今可編程控制器已吸引了大量喜愛它的用戶。 六、英文翻譯Application of the PLCApplying programmable controllers is as critical to the user, as is solving the problems that e with designing and operating efficient production processes. In fact, it is through its innovative applications that the programmable controller has excelled and attracted the large following it enjoys today. Continued development in the application area supported the evolution of certain features and capabilities that are mon today. Now we will examine the current scope of programmable controller applications, briefly look at the steps involved in implementing a system for a typical application, and consider some logical groupings of applications mon today, including basic, industry specific, and generic. What a Programmable Controller Can Do We have seen a partial listing of programmable controller applications, and while it was anything but plete, it did give a good overall look at the breadth and variety of use that programmable controllers enjoy. These systems, with such a simple and low technology heritage, have e to be capable of performing tasks that were previously considered impossible to acplish, or at least very difficult and at great expense. We will look at a survey of applications by major industry groups, and while some of the application areas are mon to many of the groups, it provides a structured method to categorize the wide variety of applications. The structure will consist of two major groupsdiscrete part manufacturing and processand several subgroups in each major group. (1) Discrete Part manufacturing Industries: ①Transportation. This industry group consists of automotive, aircraft, aerospace, railroad, and ship segments, as well as a number of smaller segments. Programmable controllers are used extensively in many of these segments, especially the automotive segment. Both the vehicle final assembly process and the various subassembly and part manufacturing processes make wide use of programmable controllers. The largest parts of these are used for sequence and motion control applications, bined with a growing overlay of data management and munications applications. Almost all of these are driven by metal cutting, forming, and assembly needs, although a glowing trend is on the plastic molding and forming area, as plastics and other engineered materials are replacing metal in some areas. The aircraft and aerospace segments share the use of programmable controllers for metal cutting and forming, but are lighter on assembly since many of the assembly processes are custom oriented, and hence cannot justify large capital outlays in hard automation. The need for factory floor data collection and analysis is very intense here, and programmable controllers play a major role in front line data is collection and concentration. Data is collected to document process integrity involving exotic and expensive metals, and for processes critical to design integrity or requiting regulatory agency documentation. The railroad and ship segments have less intense needs for programmable controllers, but one innovative use in the railroad industry involves the use of programmable controllers as trackside signal and switch control units, operating remotely and municating with a central dispatching station over phone or microwave links. ②Fabricated Metal. The fabricated metal segment consists of awide variety of subsegments and processes, and as the name suggests, most involve the use of programmable controllers for metal forming and, to a lesser extant, metal cutting. The sub segments range from manufacturing metal doors and window to producing firearms. Controllers are most often found in sequencing and motion control applications, and much use is made to acplish sophisticated material handing applications. ③Nonelectical Machinery. This segment was designed to contain a very loose arrangement of machinery manufacturers, ranging from the general to the very specific. It includes both farm and construction equipment manufacturers, internal bustion engine manufacturers, manufacturers of machine tools, and an important category called special machinery manufactures, which includes panies that produce special purpose machinery such as tobacco, shoe, elevator, and plastic molding. As you might gather, such a variety of manufacturers use programmable controllers in very large numbers. The way in which they are used is relatively straightforward, and includes a large measure of sequence control and motion control, larger facilities are also taking advantage of the munication and data management capabilities of the more sophisticated controllers. Elevators use the motion control and munication capabilities. Packaging machinery many times can use the smallest of today39。PLC應(yīng)與其它設(shè)備分別使用自己的接地裝置，[如下圖(a)]，也可以采用公共接地方式[如下圖(b)]，但禁止使用如下圖(c)所示的串聯(lián)接地方式。當(dāng)輸入端或輸出端接有感性元件時(shí)，應(yīng)在它們的兩端并聯(lián)續(xù)流二極管(對(duì)于直流電路)或阻容電路(對(duì)于交流電路)，以抑制電路斷開時(shí)產(chǎn)生的電弧對(duì)PLC的影響。傳送模擬信號(hào)的屏蔽線應(yīng)一端接地。但環(huán)境過于惡劣，干擾特別強(qiáng)烈，或安裝使用不當(dāng)，都會(huì)降低設(shè)備的可靠性，不能保證PLC正常運(yùn)行，故應(yīng)注意以下事項(xiàng)：工作環(huán)境應(yīng)考慮適中的溫度、濕度，通風(fēng)、散熱的空間，遠(yuǎn)離強(qiáng)烈的振動(dòng)，空氣中不應(yīng)有較濃的粉塵，腐蝕氣體，應(yīng)安裝空氣凈化裝置。這是用一般經(jīng)常執(zhí)行的程序，使硬件產(chǎn)生一些規(guī)定的信號(hào)，用這個(gè)信號(hào)來指示CPU處于正常狀態(tài)，萬一CPU發(fā)生故障，這個(gè)規(guī)定信號(hào)就不再出現(xiàn)，從而指示CPU的故障狀態(tài)。這樣，一旦檢測(cè)到外界環(huán)境正常后，便可恢復(fù)故障前的狀態(tài)，繼續(xù)原來的處理。PLC有比較完整的故障檢測(cè)系統(tǒng)，軟件能定期地檢測(cè)外界環(huán)境，如掉電，強(qiáng)干擾信號(hào)等等，以便及時(shí)地進(jìn)行故障處理。因此，在應(yīng)用程序中每隔幾毫秒發(fā)一次輸出命令，重寫—次輸出寄存器，以提高系統(tǒng)的可靠性。對(duì)于開關(guān)量輸入，為防止輸入觸點(diǎn)的抖動(dòng)和接觸不良，—