外文翻譯--可設(shè)計(jì)的邏輯控制器-全文預(yù)覽
【正文】 e degree in the meantime, make its application quickly increase, and make widely available many other longlost spare parts manufacture industry realm. Later on again expand to and criticize quantity to produce with continuous production line relevant of industrial realm. Along with the CIMS (calculator integration manufacturing system) development, the PLC is still used for factory by people to correspond by letter a work at present in, bee a calculator with other intelligence controllers and calculator system together prehensive control system in of importance constitute part, especially unit class and work station class. From 1969 the first set P L C publish up to now and the programmable controller about experienced three stages: First stage: The PLC capacity of the development is smaller, I/O the point be small at 120: customer saves area capacity or so scan the speed as 20~50 ms K B in the 2 KB s, the instruction is more simple and only have logic an operation and account, count etc., weave distance language to adopt a simple language sentence a predicative speech. Mainly use to make amount of switch a control on the usage. Second stage: The PLC capacity has to expand, the I/O point is from 5121024:00, customer39。 There is higher credibility and diagnosis ability, maintain easily。 Need the kit not standard exterior connects and conditionally once requested to the environment and the spot。 The physical volume is big, consume an electricity have another。Programmable logic controller A programmable logic controller (PLC) or programmable controller is a digital puter used for automation of industrial processes, such as control of machinery on factory assembly lines. Unlike generalpurpose puters, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in batterybacked or nonvolatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result. PLC and Programmable Logic Controller are registered trademarks of the AllenBradley Company, although they are widely used generically. Features The main difference from other puters is that PLC are armored for severe condition (dust, moisture, heat, cold, etc) and have the facility for extensive input/output (I/O) arrangements. These connect the PLC to sensors and actuators. PLC read limit switches, analog process variables (such as temperature and pressure), and the positions of plex positioning systems. Some even use machine vision. On the actuator side, P L C operates electric motors, pneumatic or hydraulic cylinders, magic relays or solenoids, or analog outputs. The input/output arrangements may be built into a simple PLC, or the PLC may have external I/O modules attached to a puter work that plugs into the PLC. P L C was invented as replacements for automated systems that would use hundreds or thousands of relays, cam timers, and drum sequencers. 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 when production models changed. Many of the earliest PLC express
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