【導(dǎo)讀】本課題探討了T68型臥是式鏜床的PLC改造控制系統(tǒng)的實現(xiàn)方案。實際需要和市場的需求，選擇了以三菱公司的可編程控制器作為控制方案。主要用于加工工件上的精密圓柱孔。這些孔的軸心線往往要求嚴(yán)格地平行。或垂直，相互間的距離也要求很準(zhǔn)確。率，提高設(shè)備使用效率，針對這種情況，我們用PLC控制改造其繼電器控制電路。通過對T68型臥式鏜床工作原理的分析，設(shè)計出PLC改造系統(tǒng)的控制電路，選用日本三菱公司生產(chǎn)的FX2N-48MR可編程序控制器，分配PLC的。I/O地址，設(shè)計PLC外圍電路，確定PLC的I/O接線圖。特點，列出邏輯代數(shù)表達式，采用邏輯設(shè)計方法進行梯形圖設(shè)計。統(tǒng)改造的要求，并且運行效果良好。

　　

【正文】 overed early. You can simply look at any PLC controller and see that there are several indicators in the form. of light diodes for error signalization. System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating system it also contains a user program translated forma ladder diagram to a binary form. FLASH memory contents can be changed only in case w here user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done through a serial cable in a program for application development. User memory is divided into blocks having special functions. Some parts 洛陽理工學(xué)院畢業(yè)設(shè)計論文 36 of a memory are used for storing input and output status . The real status of an input is stored either as “1”or as “0”in a specific memory bit/ each input or output has one corresponding bit in memory. Other parts of memory are used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part of the memory. PLC controller can be reprogrammed through a puter (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed through a puter if you have the software needed for programming. Today’s transmission puters are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is corrected, it is also important to read the right program into a PLC again. It is alsogood to check from time to time whether program in a PLC has not changed. This helps to avoid hazardous situations in factory rooms (some automakers have established munication works which regularly check programs in PLC controllers to ensure execution only of good programs). Almost every program for programming a PLC controller possesses various useful options such as: forced switching on and off of the system input/outputs (I/O lines), program follow up i n real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programmer can add remarks, names of input or output devices, and ments that can be useful when finding errors, or with system maintenance. Adding ments and remarks enables any technician (and not just a person who developed the system) to understand a ladder diagram right away. Comments and remarks can even quote precisely part numbers if replacements would be needed. This would speed up a repair of any problems that e up due to bad parts. The old way was such that a person who developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctly documented ladder diagram allows any technician to understand thoroughly 洛陽理工學(xué)院畢業(yè)設(shè)計論文 37 how system functions. Electrical supply is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220 VAC. On some PLC controllers you’ll find electrical supply as a separate module. Those are usually bigger PLC controllers, while small and medium series already contain the supply module. User has to determine how much current to take from I/O module to ensure that electrical supply provides appropriate amount of current. Different types of modules use different amounts of electrical current. This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs because then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs with voltage from a small supply source already incorporated into a PLC. 洛陽理工學(xué)院畢業(yè)設(shè)計論文 38 從結(jié)構(gòu)上分， PLC 分為固定式和組合式（模塊式）兩種。固定式 PLC包括 CPU 板、 I/O 板、顯示面板、內(nèi)存塊、電源等，這些元素組合成一個不可拆卸的整體。模塊式 PLC 包括 CPU 模塊、 I/O 模塊、內(nèi)存、電源模塊、底板或機架，這些模塊可以按照一定規(guī)則組合配置。 在使用者看來，不必要詳細(xì)分析 CPU 的內(nèi)部電路，但對各部分的工作機制還是應(yīng)有足夠的理解。 CPU 的控制器控制 CPU 工作，由它讀取指令、解釋指令及執(zhí)行指令。但工作節(jié)奏由震蕩信號控 制。運算器用于進行數(shù)字或邏輯運算，在控制器指揮下工作。寄存器參與運算，并存儲運算的中間結(jié)果，它也是在控制器指揮下工作。 CPU 速度和內(nèi)存容量是 PLC 的重要參數(shù)，它們決定著 PLC 的工作速度， IO 數(shù)量及軟件容量等，因此限制著控制規(guī)模。 PLC 使用系統(tǒng)存儲器（現(xiàn)在大部分采用閃存技術(shù)了）用于過程控制系統(tǒng)。除了這個操作系統(tǒng)之外，它還包括一個由梯形圖翻譯成而進制形式的用戶程序?？觳列痛鎯ζ鳎?FLASH memory）的內(nèi)容只有在改變用戶程序的時候可以被改變。 PLC 控制器比快擦型存儲器使用得更早， EPROM 存儲器比快擦型存 儲器也更早，快擦型存儲器必須用紫外線（ UV， UltraViolet Ray）燈擦除，并在編程器上進行編程。由于快擦型存儲器技術(shù)的應(yīng)用，使得這個過程大大縮短了。在應(yīng)用程序開發(fā)中，通過一個串行電纜可以對程序存儲器進行重新編程。 用戶存儲器被分成具有特殊功能的塊。一部分存儲器用來存儲輸入和輸出狀態(tài)。一個輸入的實際狀態(tài)存儲狀態(tài)存儲在專用存儲器位上，為“ 1”或者“ 0”。每一個輸入和輸出在存儲器中都有一個相應(yīng)的位。另外一部分存儲器用來存儲用戶程序中的變量的內(nèi)容。例如，定時器值，或者記數(shù)器值存放在存儲器的這個部分。 PLC 控制器可以通過計算機（通常方式）重新編程，但是也可以通過人工編程器 9 控制臺）編程。實際上，這意味著，如果你有編程所需要的軟件，早期 PLC 控制器可以通過計算機進行編程。今天的傳輸計算機是工廠自己對 PLC 控 制器進行重新編程的理想設(shè)備。這對于工業(yè)企業(yè)來說是非常重要的。一旦系統(tǒng)修改結(jié)束，將正確的程序重新讀入 PLC 控制器也是非常重要的。定期洛陽理工學(xué)院畢業(yè)設(shè)計論文 39 檢查 PLC 中的程序是否改變是非常好的事情。這有助于避免車間發(fā)生危險情況（一些汽車制造商已經(jīng)建立了通信網(wǎng)絡(luò)，可以定期檢查 PLC 中的程序，以保證運行的程序都是正確的）。 幾乎所有 用于為 PLC 控制器編程的程序都擁有各種不同的選項，例如系統(tǒng)輸入 /輸出（ I/O 線）的強制開關(guān)，程序?qū)崟r跟蹤以及圖表驗證。圖表驗證對于理解、定義失敗和故障非常必要。程序員可以添加標(biāo)記，書日和輸出設(shè)備名稱，以及對于查找錯誤或者對于系統(tǒng)維護很有用的注釋。添加注釋和標(biāo)記可以使技術(shù)人員（不僅僅是開發(fā)人員）很快理解梯形圖。注釋和標(biāo)記甚至還可以準(zhǔn)確地引用零件號，如果需要更換零件的話。這將加快由于損壞零件而引起的任何問題的修理速度。響應(yīng)的舊方法是這樣的，開發(fā)系統(tǒng)的人必須保護這個程序，他旁邊再沒有人知道系統(tǒng)是怎樣完成的。正確的 、備有證明文件的梯形圖使任何技術(shù)人員都能徹底理解系統(tǒng)的功能。 電源是為中央處理單元提供電源的。大部分 PLC 控制器的工作電壓為24VDC 或者 220VAC。在有些 PLC 控制器上，你可以看見作為獨立模塊的電源。用戶必須確定從 I/O 模塊取出多大電流來保證電源提供適當(dāng)?shù)碾娏?。不同的模塊使用不同的電流量。 該電源一般不用于啟動外部輸入或輸出。用戶必須提供獨立的電源來啟動 PLC 控制器的輸入和輸出，因為這樣可以保證 PLC 控制器的所謂“純電源”。使用純電源意味著工業(yè)環(huán)境中的電源不會嚴(yán)重影響它。有些較小的PLC 控制器從與 PLC 控制器集成在一起的小電源為它們的輸入提供電壓源。