【正文】 業(yè)設(shè)計說明書 外 文文獻(xiàn)翻譯 院 、 部： 電氣與信息工程學(xué)院 學(xué)生姓名： 指導(dǎo)教師： 職稱 副 教授 專 業(yè)： 班 級： 完成時間： PLC Theory And Applications A programmable logic controller, PLC, or programmable controller is a small puter used for automation of realworld processes, such as control of machinery on factory assembly lines. The PLC usually uses a microprocessor. The program can often control plex sequencing and is written by skilled engineers. The program is stored in batterybacked memory and/or EEPROMS. Definition is: a digital electronic puter operating system specifically designed for using in the industrial environment. It adopts a category programmable memory for its internal storage procedures, the implementation of the logical operations, sequence control, timing, counting and arithmetic operations such as useroriented instructions, and through digital or analog input / output control various types of machinery or production processes. 1 PLC Development Course In industrial production processes, a large number of switches in order to control it in a logical sequence of moves conditions, and in accordance with the logic of relations chain protection movement’s control, and a large number of discrete volume data collection. Traditionally, these functions are achieved through pneumatic or electrical control system. 1968 . GM (General Motors) pany replaced following electrical control devices, the second year, the . pany has developed a number of integrated circuits and electronic technologybased control devices, the first use of the means of the procedures applied to the electrical control, and this is the first generation programmable controller said Programmable Controller (PC) The functionality of the PLC has evolved over the years to include typical relay control, sophisticated motion control, process control, distributed control systems and plex working. Personal puter (PC for short) has been developed, in order to facilitate, but also to reflect the functional characteristics of programmable controllers. Programmable controller is named Programmable Logic Controller (PLC), now PC is often called PLC. 2 Programmable Controller Basic Tes PLC is based on puters, and applies to industrial motor controlling work site. It originated from relay control devices, but it does relay devices, the physical process of controlling through circuits, and mainly relies on the operation of PLC memory stored in the procedures for the realization of their information into and out of control. PLCs were invented as less expensive replacements for older automated systems that would use thousands of relays and cam timers. Often, a single PLC can be programmed to replace thousands of relays. Programmable controllers were initially adopted by the automotive manufacturing industry, where software revision replaced the rewiring of hardwired control panels. PLCbased puter, but can not be equated with ordinary puters. Information is transformed into a universal puter, and it is only considered by information itself. No matter information goes into and out of it。 it can be a good human interface. And the PLC will also consider the reliability of information in and out, realtime, and the use of information and other issues. Special consideration must be given to how to adapt to the industrial environment, such as the ease of installation, interference and other issues. PLC Composition PLC is divided into two forms of fixed and modular (modular) in structure. Fixed PLC includes CPU boards, I/O boards, and panels shown, within blocks, electricity. All these elements into a portfolio as a whole are not detachable. Modular PLC includes CPU Modules, I/O module, memory, power supply module, or ill bed, these modules will be in accordance with the rules of portfolio allocation. CPU Composition CPU is the core of PLC, and it plays a central role. At least one PLC has one CPU, the PLC system procedures is to receive and store the user39。 By users operating procedures, and the output will be used after the district shine upo n information。 the individual can carry out emergency treatment. Actually the process of PLC is more plex than we mentioned here, the analysis of its basic tes, some theoretical issues. If the personnel on the above can enter a change, physical realization information processing, I/O call Cumming space, time scanning method supplemented by the interruption, as a way to study and understand it, and good understanding of PLC is how to achieve control and good grasp of the basic principles of PLC points. For more indepth, in the further course of study, will make a specific presentation. 5 Programmable Controller Basic Characteristics The operating principles are those from the discussion of PLC, PLC’s input and output are mutually separated in physics, which is linked to its existing storage operation on the procedures to achieve. It into a relevant, and not rely on physics, not a line。 Information may also be trusted, and so on. It is precisely because of these characteristics of information, decisions of the basic characteristics of the PLC. The examples of PLC’s four characteristics are as follow: Functional Rich PLC functions are very rich. This was mainly related to the processing of information rich store of information systems and internal directives devices. Scores up its mand。 At the same time, also for industrial automation systems, and control much of the intelligent move created conditions. Collection rich in functions such as PLC who is notcall controls。s imagination, or other hardware and its supporting facilities. PLC39。s third characteristic, will be further introduced Second, even if the PLC failure, the maintenance i