【正文】 ecute, inside the program, movements that must be repeated for some time, but this problem can be solved with some external logic ponents. Another limitation is that the controller cannot be applied on systems that have no sequence. These limitations are a characteristic of the system that must be analyzed for each application. 4. Characteristics of the controller The controller is based on the MICROCHIP microcontroller PIC16F877 [6,7] with 40 pins, and it has all the resources needed for this project .It has enough pins for all the ponents, serial munication implemented in circuit, EEPROM memory to save all the configuration of the system and the sequence of steps. For the execution of the main program, it offers plete resources as timers and interruptions. The list of resources of the controller was created to explore all the capacity of the microcontroller to make it as plete as possible. During the step, the program chooses how to use the resources reading the configuration string of the step. This string has two bytes for digital inputs, one used as a mask and the other one used as a value expected. One byte is used to configure the outputs value. One bytes more is used for the internal timer , the analog input or timeout. The EEPROM memory inside is 256 bytes length that is enough to save the string of the steps, with this characteristic it is possible to save between 48 steps （ Table 1） . The controller () has also a display and some buttons that are used with an interactive menu to program the sequence of steps and other configurations. . Interaction ponents For the real application the controller must have some elements to interact with the final user and to offer a plete monitoring of the system resources that are available to the designer while creating the logic control of the pneumatic system (): ?Interactive mode of work。 2byte: mask for the inputs。 the system made with microcontroller is an alternative that works in a simple way. 。 4byte: value for the outputs。 the speed is regulated by a flowing control valve. It was the second step. B and C are examples of actuators working together, while B pushes an object slowly, C repeats its work for some time. When B reaches the final position, C stops immediately its cycle and es back to the initial position. The actuator D is a single acting one with spring return and works together with the back of C, it is the third step. D works making very fast forward and backward movement, just one time. Its backward movement is the fourth step. D could be a tool to make a hole on the object. When D reaches the initial position, A and B return too, it is the fifth step. Fig. 6 shows the first part of the designing process where all the movements of each step should be defined [2]. (A+) means that the actuator A moves to the advanced position and (A?) to the initial position. The movements that happen at the same time are joined together in the same step. The system has five steps. These two representations of the system (Figs. 5 and 6) together are enough to describe correctly all the sequence. With them is possible to design the whole control circuit with the necessary logic ponents. But till this time, it is not a plete system, because it is missing some auxiliary elements that are not included in this draws because they work in parallel with the main sequence. These auxiliary elements give more function to the circuit and are very important to the final application?？傊覀兊倪@個(gè)系統(tǒng)是基于微控制器而設(shè)計(jì)，簡(jiǎn)單快捷。利用電氣系統(tǒng)，我們的項(xiàng)目應(yīng)用了相同的技術(shù)，但同時(shí)我們的設(shè)計(jì)更加直接。（圖 9 和 10） 7 結(jié)論 這種控制器是專門為這一項(xiàng)目所設(shè)計(jì)的。 序列獨(dú)自被定義，但每一步驟只被輸入和輸出端描述。 使用傳統(tǒng)的 PLC的 ， 如圖 7， 8所示，在繪制接口處的電圖表時(shí)，要注意線路的邏輯。但是 ,如前面提到的那樣 ,使用一個(gè) PLC或特定的控制器 ， 這種控制就變得比較容易的，而且系統(tǒng)的精密性也會(huì)提高。圖 7和 8顯示的是在沒有使用控制器的情況下會(huì)發(fā)生的一些結(jié)果。 對(duì)于程序的最后運(yùn)行， 這些輔助設(shè)施十分的重要，因?yàn)樗麄兡苁咕€路有更多的功能。這個(gè)系統(tǒng)共有有五個(gè)步驟。當(dāng) D返回開始的位置時(shí)候 ， A和 B也同時(shí)返回，這是第五個(gè)步驟。 圖 5 A， B， C， D 傳動(dòng)裝置時(shí)間曲線 第三步，當(dāng) B到達(dá)最后的位置時(shí)候 ， C停止立刻它的循環(huán)運(yùn)動(dòng)并且回到開始的位置。 主動(dòng)器 A， B 和C是兩倍的，只有 D是單倍的。 在每個(gè)步驟中，系統(tǒng)的狀態(tài)被儲(chǔ)存，同時(shí)它也在顯示器上被顯示。 使用者能利用接口配置一連串定義序列的步驟位元組。他們可以重新啟動(dòng)程序，隨時(shí)恢復(fù)到程序的原有狀態(tài)。 嘀嘀聲用來提示重要警示，停止，開始和一些緊急情況的發(fā)生 亮燈表示接通電源，和輸入，輸出狀態(tài)。 EEPROM 記憶內(nèi)部是 256 位元組，可以儲(chǔ)藏所有步驟的運(yùn)行 ,即可以儲(chǔ)藏 48 個(gè)步驟之間的所有運(yùn)行。 我們做出了控制器的資源目錄，想盡可能的使它變的完善。這些局限性也是這個(gè)系統(tǒng)的特性，這種系統(tǒng)的每一個(gè)應(yīng)用都必須要有相應(yīng)的系統(tǒng)分析。 傳統(tǒng)的 PLC 的系統(tǒng)運(yùn)行程序是一個(gè)循環(huán)的線路：輸入一個(gè)圖像 ,運(yùn)行所有的內(nèi)部程序 , 然后升級(jí)輸出的狀態(tài)。 每個(gè)部分都有程序的一個(gè)步驟結(jié)構(gòu)。在設(shè)計(jì)的最后階段，系統(tǒng)中會(huì)有一個(gè)從來不變化的序列和明確的輸入和輸出端。我們能夠很清楚的看到每一步驟和下一個(gè)步驟之間的聯(lián)系。它包括根據(jù)發(fā)動(dòng)機(jī)