【正文】
d, largescale integrated circuits even when the Plc is no longer the only logical (IC) judgement functions also have data processing, PID conditioning and data munications functions. International Electrotechnical Commission (IEC) standards promulgated programmable controller for programmable controller draft made the following definition : programmable controller is a digital electronic puters operating system, specifically for applications in the industrial design environment. It used programmable memory, used to implement logic in their internal storage operations, sequence control, timing, counting and arithmetic operations, such as operating instructions, and through digital and analog input and output, the control of various types of machinery or production processes. Programmable controller and related peripherals, and industrial control systems easily linked to form a whole, to expand its functional design. Programmable controller for the user, is a noncontact equipment, the procedures can be changed to change production processes. The programmable controller has bee a powerful tool for factory automation, widely popular replication. 4 Programmable controller is useroriented industries dedicated control puter, with many distinctive features. ① First, high reliability, antiinterference capability。 可編程控制器對用戶來說,是一種無觸點 設備,改變程序即可改變生產工藝。 70 年代中期以后, PLC 已廣泛地使用微處理器作為中央處理器,輸入輸出模塊和外圍電路也都采用了中、大規(guī)模甚至超大規(guī)模的集成電路,這時的 PLC已不再是僅有邏 輯 (Logic)判斷功能,還同時具有數(shù)據處理、 PID 調節(jié)和數(shù)據通信功能。以執(zhí)行邏輯判斷、計時、計數(shù)等順序控制功能。提出 PLC 概念的是美國通用汽車公司。國際電工委員會 (IEC)頒布的可編程控制器標準草案中對可編程控制器作了如下的定義:可編程控制器是一種數(shù)字運算操作的電子系統(tǒng),專為在工業(yè)環(huán)境下應用而設計。目前,可編程控制器已成為工廠自動化的強有力工具,得到了廣泛的普及推廣應用。 ② Second programming visual, simple。小型的彩燈多為采用霓虹燈管做成各種各樣和多種色彩的燈管,或是以日光燈、白熾燈作為光源,另配大型廣告語、宣傳畫來達到效果。針對 PLC日益得到廣泛應用的現(xiàn)狀 ,本文介紹 PLC 在不同變化類型的彩燈控制中的應用,燈的亮滅、閃爍時間及流動方向的控制均通過 PLC 來達到控制要求。變幻燈則包括字形變化、色彩變化、位置變化等,其主要特點是在整個工作過程中周期性地花樣變化,但頻率不高。 2 PLC的簡介 PLC的定義 Programmable Logic Controller 簡稱為 PLC,即可編程控制器,是指以計算機技術為基礎的新型工業(yè)控制裝置。 個人計算機(簡稱 PC)發(fā)展起來后,為了方便,也為了反映可編程控制器的功能