【正文】 ata signal and the clock signals to be carry on by the CPU to send out at the same time, this needs to all want the specialized clock signal each other to carry on the transmission and connect to send, and is constrained, the characteristics of this kind of method lies in its speed very quick, but correspond work time of take up the CPU and also want to be long oppositely, at the same time the technique difficulty also very big. Its request lies in can39。t send out and accept at the same time, for example when you make a phone call is to can39。t give the superior reply。t guarantee the equipments by the control of the single machine, but pass the information exchanges of the equipments and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will arrive wrapping information feedback to examine the place, and examine the information of the place to also want the feedback to packing. Pass the information share thus to make both the chain connect, being a total body, the match of your that thus make is more close, at each other attain to reflect the result that mutually flick. The PLC correspondence has already e more more body now its value, at the PLC and correspondence between PLCs, can pass the munication of the information and the share of the datas to guarantee that of the equipments moderates mutually, the result that arrive already to repair with each other. Data conversion the adoption RS232 between PLC connect to e to the transmission data, but the RS232 pick up a people and can guarantee 10 meters only of deliver the distance, if in the distance of 1000 meters we can pass the RS485 to carry on the correspondence, the longer distance can pass the MODEL only to carry on deliver. The PLC data transmission is just to be called a form to it in a piece of and continuous address that the data of the inner part delivers the other party, we, the PLC of the other party passes to read data in the watch to carry on the operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for example today of oil price rise, I want to deliver the price of the oil price to lose the oil ally on board, that is the share of the data。s power, the one who make operate reduces the otiose error. Currently the HMI factory is also more and more, the function is also more and more strong, the price is also more and more low, the noodles of the usage are wide more and more. The HMI foreground can say that think 176。 But lead even is a fatal error greatly is what we can39。 The I/ O add inner part is tired the input and output system of the machine and exterior link, and deposit the related data into the procedure saving machine or data saving machine。And the PLC emergence also became the epochmaking topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide. The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculationses of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but theexportation equipments direct conjunction of the small power can. PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people39。s brain and calculators, with the mode that person39。t guarantee the request of the higher quantity and high new the image of the technique business enterprise. The people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel39。 the operation that list depends the artificial has already can39。 PLC 的出現(xiàn)已經(jīng)足足影響了幾代人，我們也從上一輩的經(jīng)驗(yàn)中獲取了更多的知識和教訓(xùn)，來不斷的發(fā)展 PLC技術(shù)，將它推向更高浪潮。組態(tài)軟件可以將所有的這些硬件連接起來，通過更直觀的動畫圖片來進(jìn)行控制，并可以通過互聯(lián)網(wǎng)在異地 進(jìn)行控制，像神舟五號的發(fā)射就是采用這種辦法來使飛船升空。程序重新開始運(yùn)行，但對中斷不會進(jìn)行破壞。 你也許聽過太多的這個詞 :“死機(jī)”，大致的意思是 CPU工作量過大，內(nèi)部資源不足等情況造成程序無法運(yùn)行。它在PLC執(zhí)行程序時一旦發(fā)現(xiàn)高級計數(shù)器對應(yīng)的中斷，就會立即放下手上的工作。 當(dāng)我們在工作完一個工件時，給 PLC一個信號，將 PLC的內(nèi)部計數(shù)器加 1來計算我們一天的工作量時，一個簡單的 計數(shù)器能解決問題，當(dāng)然它們也能夠在掉電的情況下保持?jǐn)?shù)據(jù)，促使數(shù)據(jù)不丟失，這也是我們所渴望的。急停按鈕連接 PLC內(nèi)部 CPU的內(nèi)部 I/O接口上，當(dāng)按鈕給 CPU一個外部觸發(fā)信號時， CPU對 I/O進(jìn)行再次檢測，當(dāng)確認(rèn)有外部觸發(fā)信號時， CPU保護(hù)現(xiàn)場并將程序計數(shù)器自動轉(zhuǎn)到相應(yīng)的外部 I/O中斷程序中去，當(dāng)外部中斷程序