【正文】 hrough person39。 PLC的發(fā)展已經(jīng)從單一的模式進入了通信的網(wǎng)絡(luò)時代，并同其它的工控網(wǎng)板和 I/O卡板輕易的進行共享。有一點可以說明的是我們一般會把急停按鈕的外部中斷升至最高級別，從而保證安全。CPU總是按照我們的意愿去做應(yīng)該做的事情，但你錯誤的給它一件事情，它也會同樣的去做，這一點我們必須注意。 而異步是應(yīng)用范圍最廣泛的，這得益于它的技術(shù)難度相對要小、同時不需要配制專門的時鐘信號、它的特點在于，它的數(shù)據(jù)是間隔性的，離散性的發(fā)送和接受，當(dāng) CPU 太忙的時候可以停頓性去工作，在硬件上也減少了難度，同時數(shù)據(jù)的丟失相對要少，我們可以通過數(shù)據(jù)的檢測來觀察我們發(fā)送的數(shù)據(jù)是否有錯 誤，像奇偶法、累加法和八位效驗法等，都可以用來幫助我們檢測發(fā)送的數(shù)據(jù)是否有錯誤發(fā)生，通過反饋來進行辨別。 PLC的數(shù)據(jù)傳送只是將內(nèi)部的數(shù)據(jù)傳送到對方的一塊連續(xù)的地址中，我們把它稱為一個表，對方的 PLC通過讀取表中的數(shù)據(jù)來進行操作。并且能夠通過編寫功能幫助程序來提供各種力所能及的幫助，使得操作者減少不必要的失誤。單靠人工的操作已不能滿足于目前的制造業(yè)前景 ,也無法保證更高質(zhì)量的要求和高新技術(shù)企業(yè)的形象 . 人們在生產(chǎn)實踐中看到 ,自動化給人們帶來了極大的便利和產(chǎn)品質(zhì)量上的保證 ,同時也減輕了人員的勞動強度 ,減少了人員上的編制 .在許多復(fù)雜的生產(chǎn)過程中難以實現(xiàn)的目標(biāo)控制、整體優(yōu)化、最佳決策等 ,熟練的操作工、技術(shù)人員或?qū)＜摇⒐芾碚邊s能夠容易判斷和操作 ,可以獲得滿意的效果 .人工智能的研究目標(biāo)正是利用計算機來實現(xiàn)、模擬這些智能行為 ,通過人腦與計算機協(xié)調(diào)工作 ,以人機結(jié)合的模式 ,為解決十分復(fù)雜的問題尋找最佳的途徑 我們在各種場合看到了繼電器連接的控制，那已經(jīng)是時代的過去，如今的繼電器只能作為低端的基層控制模塊或者簡單的設(shè)備中使用到；而 PLC的出現(xiàn)也成為了劃時代的主題，通過極其穩(wěn)定的硬件穿插靈活的軟件控制，使得自動化走向了新的高潮。 以上僅僅是 PLC的優(yōu)點之一，這也是人們比較容易理解的一部分，在很多的設(shè)備中，人們已不再希望看到太多的控制按鈕，它們不但容易損壞而且極易產(chǎn)生人為的失誤，小的并不是主要的失誤也許你還能夠接受；但過大的甚至是致命的失誤是我們無法容忍的。這樣通過信息共享來使得兩者之間鏈接起來，形成一個共體，從而使的兩者間的配合更加的緊密，在彼此間達到映影相揮的效果。 信息輸送的過程也有同步和異步之分：同步的意義在于發(fā)送數(shù)據(jù)時數(shù)據(jù)線和時鐘線是同步的，也就是數(shù)據(jù)信號和時鐘信號同時由 CPU 進行發(fā)送，這需要彼此都要專門的時鐘信號來進行傳送和接送，并且是強制性的，這種方法的特點在于它的速度極快、但相應(yīng)占用 CPU 的工作時間也相對的要長、同時 技術(shù)難度也非常的大。很多的情況下我們總喜歡采用串并轉(zhuǎn)換芯片來進行傳輸，這種情況下不需要我們進行過于復(fù)雜的寄存器設(shè)置了，而直接通過數(shù)據(jù)傳送指令進行數(shù)據(jù)交流，但在通信中并不是一個十分可行的辦法，因為在發(fā)送數(shù)據(jù)的時候?qū)Ψ降?PLC 必須一直等待你的數(shù)據(jù)輸出，它不能去做其他的工作。這樣講也許你并不能完全理解中斷的內(nèi)部結(jié)構(gòu)和操作順序，我們做一個小小的例子來說明 . 每一個設(shè)備總是不會忘記有一個按鈕，它也是在我們遇到緊急情況時使用的，那就是急停按鈕。 你也許聽過太多的這個詞 :“死機”，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行。 the operation that list depends the artificial has already 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。t give the superior reply。t prehend the internal structure and operation orders of the interruption pletely also, we do a very small example to explain. Each equipments always will not fet a button, it also is at we meet the urgent circumstance use of, that is nasty to stop the button. When we meet the Human body trouble and surprised circumstances we as long as press it, the machine stops alloperations immediately, and wait for processing the over surprised empress recover the operation stop the internal I/ O of the internal CPU of the button conjunction PLC to connect up, be to press button an exterior to trigger signal for CPU, the CPU carries on to the I/ O to examine again, being to confirm to have the exterior to trigger the signal, CPU protection the spot breaks off procedure counts the machine turn the homologous exterior I/ O automatically in the procedure to go to also, be exterior interruption procedure processing plete, the procedure counts the machine to return the main procedure to continue to 1:00 can what to explain is we generally would nasty stop the button of exterior break off to rise to the tallest Class, thus guarantee the safety. When we are work a work piece, giving the PLC a signal, counting PLC inner part the machine add 1 to pute us for a day of workload, a count the machine and can solve problem in brief, certainly they also can keep the data under the condition of dropping the electricity, urging the data not to throw to lose, this is also what we hope earnestly. The PLC still has the function that the high class counts the machine, being us while accept some datas of high speed, the high speed that here say is the data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously, calculating highspeed signal of the data processor DSP etc., we will adopt the high class to count the machine to help we carry on count. It at the PLC carries out the procedure once discover that the high class counts the machine to should of interruption, will let go of the work on the hand immediately. The trapezoid diagram procedure that passes by to weave the distance again explains the high class for us to carry out procedure to count machine would automatic performance to should of work, thus rise the Class that the high class counts the machine to high one Class. You heard too many this phrases perhaps: crash, the meaning that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can39。t send out and accept at the same time, for example when you make a phone call is to can39。 But lead even is a fatal error greatly is what we can39。t guarantee the request of the higher quantity and hi