【正文】 存器的通斷狀態(tài)在輸出刷新階段送至輸出鎖存器中，并通過一定的方式（繼電器、晶體管或晶閘管）輸出，驅(qū)動相應(yīng)輸出設(shè)備工作。執(zhí)行用戶程序階段：按用戶程序指令存放的先后順序掃描執(zhí)行每條指令，經(jīng)相應(yīng)的運算和處理后，其結(jié)果再寫入輸出狀態(tài)寄存器中，輸出狀態(tài)寄存器中所有的內(nèi)容隨著程序的執(zhí)行而改變。在每次掃描過程中，還要完成對輸入信號的采樣和對輸出狀態(tài)的刷新等工作。通過專用的PC/PPI電纜線將PLC與電腦聯(lián)接，并利用專用的編程軟件進(jìn)行電腦編程和監(jiān)控。 外部設(shè)備接口 此接口可將打印機(jī)、條碼掃描儀,變頻器等外部設(shè)備與主機(jī)相聯(lián)，以完成相應(yīng)的操作。輸出接口是將主機(jī)經(jīng)處理后的結(jié)果通過功放電路去驅(qū)動輸出設(shè)備（如接觸器、電磁閥、指示燈等）。CPU是PLC的核心，它用以運行用戶程序、監(jiān)控輸入/輸出接口狀態(tài)、做出邏輯判斷和進(jìn)行數(shù)據(jù)處理，即讀取輸入變量、完成用戶指令規(guī)定的各種操作，將結(jié)果送到輸出端，并響應(yīng)外部設(shè)備（如電腦、打印機(jī)等）的請求以及進(jìn)行各種內(nèi)部判斷等。PLC是微機(jī)技術(shù)與傳統(tǒng)的繼電接觸控制技術(shù)相結(jié)合的產(chǎn)物，它克服了繼電接觸控制系統(tǒng)中的機(jī)械觸點的接線復(fù)雜、可靠性低、功耗高、通用性和靈活性差的缺點，充分利用了微處理器的優(yōu)點，又照顧到現(xiàn)場電氣操作維修人員的技能與習(xí)慣，特別是PLC的程序編制，不需要專門的計算機(jī)編程語言知識，而是采用了一套以繼電器梯形圖為基礎(chǔ)的簡單指令形式，使用戶程序編制形象、直觀、方便易學(xué)；調(diào)試與查錯也都很方便。由于這些特點，可編程控制器問世以后很快受到工業(yè)控制界的歡迎，并得到迅速的發(fā)展。其基本設(shè)計思想是把計算機(jī)功能完善、靈活、通用等優(yōu)點和繼電器控制系統(tǒng)的簡單易懂、操作方便、價格便宜等優(yōu)點結(jié)合起來，控制器的硬件是標(biāo)準(zhǔn)的、通用的。s consumption levels continue to increase, private vehicles is increasing. Of people, cars and more roads have less traffic status is obvious. Therefore, the adoption of effective methods to control traffic lights is imperative. PLC intelligent control principle is the core of the control system using PLC northsouth direction to eastwest direction or scale of the vehicle by the number of subfile, the appropriate thing given the green light northsouth direction and length of time is also subfile according to certain rules. This scale can be achieved given the green light at traffic duration, to achieve maximum release a car to reduce the stagnation of vehicles crossing to ease traffic congestion, to achieve optimal control, thus improving the efficiency of traffic control system. PLC structure is simple, easy programming, high reliability, has been widely used for industrial process and location of the automatic control. The use of the PLC has the characteristics of environmental adaptability, while its internal timer resources are very rich, the current widespread use of the progressive signal for precise control, particularly control of multifork can be easily achieved. Therefore, the PLC is now increasingly used in traffic lights system. PLC also has a munications networking capabilities, the same signal on the road to form a unified LAN management, and can shorten the waiting time for vehicle traffic, to achieve scientific management. In realtime detection and application of automatic control systems PLC, PLC is often used as a core ponent. Key words: traffic lights, control systems, configuration design1 可編程控制系統(tǒng)介紹 PLC簡介隨著微處理器，計算機(jī)的和數(shù)字通訊技術(shù)的飛速發(fā)展，計算機(jī)控制技術(shù)已經(jīng)滲透到所有工業(yè)領(lǐng)域。因此現(xiàn)在越來越多地將PLC應(yīng)用于交通燈系統(tǒng)中。人多、車多道路少的道路交通狀況已經(jīng)很明顯了。社會的發(fā)展，人們的消費水平不斷的提高，私人車輛不斷的增加。由于PLC具有對使用環(huán)境適應(yīng)性強(qiáng)的特性，同時其內(nèi)部定時器資源十分豐富，可對目前普遍使用的“漸進(jìn)式”信號燈進(jìn)行精確控制，特別對多岔路口的控制可方便地實現(xiàn)。關(guān)鍵字：PLC、交通燈、控制系統(tǒng)、組態(tài)設(shè)計Abstract: Today, traffic lights installed on the crossing at all, to ease the traffic of vehicles has bee the most mon and most effective means. Social development, people39。可編程控制器是60年代末在美國首先出現(xiàn)的，當(dāng)時叫可編程邏輯控制器，目的是用來取代繼電器，以執(zhí)行邏輯判斷、計時、計數(shù)等順序控制功能。另一方面，從制造生產(chǎn)可編程控制器的廠商角度看，在制造階段不需要根據(jù)用戶的要求專門設(shè)計控制器，