【正文】 est and most powerful programmable controller features. ④Electrical and Electronic. This segment is made up of manufacturers ranging from those that produce televisions and radios to those that make batteries. Machinery that is used in these manufacturing processes includes some batch processing, as well as a measure of sequential control (material handling), and motion control (ponent insertion). Other fertile areas include automatic assembly, automatic storage and retrieval systems, and testing systems. Again, as in the other segments we have examined so far, larger facilities are using local area networks to take advantage of the munication and data management features of the newer controllers. Also as with other segment, we find many, many standalone machine applications using small to mediumsized controllers, including queuing conveyor systems and specially designed packaging machines. (2) Process Industries: ①Food. The food processing industry is one that has a wide variety of programmable controller applications, ranging form the batch processing of fluid milk to the batch processing of beer, all the way to the packaging of both products. Material handling applications are mon, and include both bulk (the controlled movement of a continuous stream of produce), and unit (the controlled movement of individual units of product). PID closed loop control is mon with the need to regulate flow and level of foods in process, as well as the temperature regulation of certain cooking and sterilizing processes. Government regulation of many foodrelated processes calls for meticulous documentation and data gathering of process parameters to guarantee proper food quality. All of these applications needs call on the natural strengths of programmable controllers, and use a board sample of control schemes. ②Chemical. The chemical industry consists of a number of related segments, including pharmaceuticals, paints, and engineered materials, such as plastics. This group relies on the programmable controller not for primary continuous process control needs, but is used in conjunction with the process puter. While the process puter has mand of the many process loops involved in a continuous process, the programmable controller, connected through a munication interface, operates the various pump motors and supply valves involved in the process. In smaller facilities that produce products utilizing more batch processing, programmable controllers are sometimes used as the primary control devices. A perhaps surprisingly, large application area in the chemical segment is the packaging area. Programmable controllers, properly applied, make excellent control devices for highspeed packaging processes. ③Primary Metals. Primary metals are aluminum, steel, etc. Theproduction of these metals relies on programmable controllers for many and various needs. Most of these relate to the sequencing and movement of the metal, in its liquid, semisolid, and finished states. Continuous casting processes, hot and cold rolling processes, and coding and inline storage of finished materials all use sequence and motion control heavily. Integration with variable speed drives is mon. Also mon are uses of controllers for control of slitters and coilers. In some facilities, programmable controllers are also used for batch mixing and weighing of materials at the front of the process. This involves PID control and regulation of weights and flows, as well as the integration of bulk conveyor control. ④ Paper. Paper industry applications include both the original creation from wood fiber, and the conversion to finished goods such as corrugated boxes and stationary grade paper. Programmable controllers are used here in ways similar to those in the primary metals segment. This should e as no surprise since both are web processes. The wet end of the process is now experiencing more applications of programmable controllers for loop process control. The coordination of multiple variable speed drives on typical paper machine is acplished by a bination of programmable controllers and special purpose controls. The converting process, normally asynchronous from the primary process, involves a number of cutting, folding, and assembly processes using motion and sequence control.⑤ Electric Utilities. The electric utility industry, like many other process industries, uses a process puter for the actual control of the generation process, but use programmable controllers to perform ancillary functions. These include the bulk material handling of coal into the generation facility, the removal of waste ashes from the process, and the control of the scrubbers used to clean the byproduct process air. These are connected to the main process puter by a munication link.可編程序控制器的應(yīng)用 當(dāng)要解決來(lái)自設(shè)計(jì)和操作高效生產(chǎn)過程中的問題時(shí)，對(duì)于用戶來(lái)講，使用可編程控制器是非常重要的。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。在應(yīng)用領(lǐng)域上的持續(xù)發(fā)展支持了某種特色及能力的演變，這在當(dāng)今是很普遍的。現(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。可編程序控制器可以做的事我們看過可編程序控制器應(yīng)用的部分列表，但那并不完善 ，它可以提供好的一般的可編程序控制器大量的各種各樣的用途。一些簡(jiǎn)單且技術(shù)較低的系統(tǒng)如果用來(lái)操作根本不可能完成或非常難得工作將造成很大的損失。我們將學(xué)習(xí)在工業(yè)方面的應(yīng)用，及在其它方面較普遍的應(yīng)用，它將把各種各樣的應(yīng)用按結(jié)構(gòu)進(jìn)行分類。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)。①、運(yùn)輸業(yè) 這部分包括自動(dòng)化裝置，飛機(jī)、宇宙飛船、鐵路、航運(yùn)以及還有一些小的應(yīng)用范圍。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。機(jī)械的最后裝配過程和各種輔助裝配及部分制造的工序都會(huì)廣泛的用到可編程序控制器。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。盡量以后的發(fā)展趨勢(shì)是塑料鑄模，現(xiàn)在塑料和其它可鑄材料在一些領(lǐng)域已取代了金屬，但幾乎大多數(shù)還是用于金屬是的切割，鑄模以及裝配的需要。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。而不用引燃機(jī)的裝配因?yàn)楹芏嘌b配工序都是按慣例進(jìn)行的，所以就不可避免大量的資金花費(fèi)在較難的自動(dòng)化操作上。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。在鐵路和航運(yùn)部分對(duì)可編程序控制器精確的要求相對(duì)就少一些。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。② 金屬制造。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。其中輔助部分的范圍是從金屬門窗的制造到武器的生產(chǎn)?？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。這部分的設(shè)計(jì)所包含的制造業(yè)非常廣泛，它的范圍可從一般的制造行業(yè)到特殊的制造行業(yè)。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。如果能集中計(jì)算的話，那將還有很多各種各樣的行業(yè)在使用可編程序控制器。使用它們的方法相對(duì)來(lái)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