PLC控制系統(tǒng)是在傳統(tǒng)的順序控制器的基礎(chǔ)上引入了微電子技術(shù)、計(jì)算機(jī)技術(shù)、自動(dòng)控制技術(shù)和通訊技術(shù)而形成的一代新型工業(yè)控制裝置，目的是用來取代繼電器、執(zhí)行邏輯、記時(shí)、計(jì)數(shù)等順序控制功能，建立柔性的遠(yuǎn)程控制系統(tǒng)。具有通用性強(qiáng)、使用方便、適應(yīng)面廣、可靠性高、抗干擾能力強(qiáng)、編程簡單等特點(diǎn)。

　　PLC內(nèi)部工作方式一般是采用循環(huán)掃描工作方式，在一些大、中型的PLC中增加了中斷工作方式。當(dāng)用戶將用戶程序調(diào)試完成后，通過編程器將其程序?qū)懭隤LC存儲(chǔ)器中，同時(shí)將現(xiàn)場的輸入信號(hào)和被控制的執(zhí)行元件相應(yīng)的連接在輸入模塊的輸入端和輸出模塊的輸出端，接著將PLC工作方式選擇為運(yùn)行工作方式，后面的工作就由PLC根據(jù)用戶程序去完成

PLC control system is a new generation of industrial control device based on the traditional sequential controller, which introduces microelectronics technology, computer technology, automatic control technology and communication technology. Its purpose is to replace the sequential control functions such as relay, executive logic, time recording and counting, and establish a flexible remote control system. It has the characteristics of strong universality, convenient use, wide adaptability, high reliability, strong anti-interference ability, simple programming and so on.
The internal working mode of PLC generally adopts the circular scanning working mode, and the interrupt working mode is added in some large and medium-sized PLCs. After debugging the user program, the user writes the program into the PLC memory through the programmer. At the same time, the on-site input signal and the controlled actuator are correspondingly connected to the input end of the input module and the output end of the output module. Then, the PLC working mode is selected as the operation working mode, and the subsequent work is completed by the PLC according to the user program