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plc_基礎(chǔ)原理----中英文翻譯.doc

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plc_基礎(chǔ)原理----中英文翻譯,1.1 motivationprogrammable logic controllers (plc), a computing device invented by richard e. morley in 1968, have been widely used in industry including manufa...
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此文檔由會員 wanli1988go 發(fā)布

1.1 Motivation
Programmable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, 1999].
Although PC based control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices of computing hardware is steadily dropping. The inventor of the PLC, Richard E Morley, fairly considers the PLC market as a 5-billion industry at the present time.
1.1動力
1968年,Richard E. Morley創(chuàng)造出了新一代工業(yè)控制裝置可編程邏輯控制器(PLC),現(xiàn)在,PLC已經(jīng)被廣泛應用于工業(yè)領(lǐng)域,包括機械制造也、運輸系統(tǒng)、化學過程設(shè)備、等許多其他領(lǐng)域。初期可編程控制器只是用一種類似于語言的軟件邏輯于代替繼電器硬件邏輯,并且使開發(fā)時間由6個月縮短到6天。
雖然計算機控制技術(shù)已經(jīng)產(chǎn)生,但是PLC控制因為它的高性能、成本低、并且對惡劣的環(huán)境有很強的適應能力而在工業(yè)控制的廣泛應用中保持優(yōu)勢。而且,盡管硬件的價格在逐漸下跌,據(jù)估計,根據(jù)Frost和Sullivan對PLC市場的調(diào)查研究表明,每年銷售硬件的價格要比銷售PLC的價格(一千五百萬)至少多出八十億美元。PLC的創(chuàng)造者Richard E. Morley十分肯定的認為目前PLC市場是一個價值五十億的工業(yè)