外文翻譯--plc控制系統(tǒng)設(shè)計(jì)的要點(diǎn)-wenkub
2022-12-15 04:21:16 本頁(yè)面
【正文】 he 15 machines. ②Implementing Change and Correcting Errors. With a wired relaytype panel, any program alterations require time for rewriting of panels and devices. When a PLC program circuit or sequence design change is made, the PLC program can be changed from a keyboard sequence in a metter of minutes. No rewiring is required for a PLCcontrolled system.③Large quantities of contacts. The PLC has a large number of contacts for each coil available in its that a panelwired relay has four contacts and all are in use when a design change requiring three more contacts is made. Time would have to be taken to procure and install a new relay or relay contact block. Using a PLC, howere, only three more contacts would be typed in. the three contact would be automatically available in the PLC. Indeed, a hundred contacts can be used from one relayif sufficient puter memory is available. ④Lower cost. Increased technology makes it possible to condense more functions into smaller and less expensive packages. Now you can purchase a PLC with numerous relays, timers and counters, a sequencer, and other function for a few hundred dollars.⑤Pilot Running. A PLC programmed circuit can be evaluated in the office or lab. The program can be typed in, tested, observed, and modified if needed, saving valuable factory time. In contrast, conventional relay systems have been tested on the factory floor, which can be very time consuming.⑥Visual Observation. A PLC circuit’s operation can be seen during operation directly on a CRT screen. The operation or misoperation of a circuit can be observed as it happens. Logic paths light up on the screen as they are energized. Troubleshooting can be done more quickly during visual observation. In advanced PLC systems, an operator message can be programmed for each possible malfunction.In advanced PLC systems, an operator message can be programmed for each possible malfunction. The malfunction description appears on the screen when the malfunction is detected by the PLC logic. Advanced PLC systems also may have descriptions of the function of each circuit ponent. ⑦Speed of Operation. Relays can take an unacceptable amount of time to actuate. The operational speed for the PLC program is very fast. The speed for the PLC logic operation is determined by scan time, which is a matter of milliseconds.⑧Ladder or Boolean Programming Method. The PLC programming can be acplished in the ladder mode by an electrician or technician. Alternatively, a PLC programmer who works in digital or Boolean control systems can also easily perform PLC programming. In modern industrial production equipment, and large numbers of simulations of the control devices, such as the cease electrical, electromagnetic devices to turn, the number of products, temperature, Ap power, and set the flow control, the automatic control of the industrial site, If a programmable controller (PLC) to resolve the issue has bee a cybernetic one of the most effective tools, this article describes Plc control system design should be noted. Hardware purchase many products currently on the market Plc, with the exception of domestic brands, foreign : Japan Omron, Mitsubishi, FUJJ, ANASONIC, Germany Siemens, Korean LG. In recent years, Plc greater
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