畢設(shè)設(shè)計(jì)外文翻譯-應(yīng)用于電氣系統(tǒng)的可編程序控制器-電氣類-閱讀頁
2025-06-05 23:09本頁面
【正文】 ces and stays in specified position till the end of the cycle, it could work fixing an object to the next action for example (Fig. 5) , it is the first step. When A reaches the end position, actuator C starts his work together with B, making as many cycles as possible during the advancing of B. It depends on how fast actuator B is advancing。 the most important of them is the parallel circuit linked with all the others steps. That circuit should be able to stop the sequence at any time and change the state of the actuators to a specific position. This kind of circuit can be used as a reset or emergency buttons. The next Figs. 7 and 8 show the result of using the method without the controller. These pictures are the electric diagram of the control circuit of the example, including sensors, buttons and the coils of the electrical valves. The auxiliary elements are included, like the automatic/manual switcher that permit a continuous work and the two start buttons that make the operator of a machine use their two hands to start the process, reducing the risk of accidents. 6. Changing the example to a user program In the previous chapter, the electropneumatic circuits were presented, used to begin the study of the requires to control a system that work with steps and must offer all the functional elements to be used in a real application. But, as explained above, using a PLC or this specific controller, the control bees easier and the plexity can be increase also. Table 2 shows a resume of the elements that are necessary to control the presented example. With the time diagram, the step sequence and the elements of the system described in Table 2 and Figs. 5 and 6 it is possible to create the configuration of the steps that can be sent to the controller (Tables 3 and 4). While using a conventional PLC, the user should pay attention to the logic of the circuit when drawing the electric diagram on the interface (Figs. 7 and 8), using the programmable controller, described in this work, the user must know only the concept o f the method and program only the configuration of each step. It means that, with a conventional PLC, the user must draw the relation between the lines and the draw makes it hard to differentiate the steps of the sequence. Normally, one needs to execute a simulation on the interface to find mistakes on the logic The new programming allows that the configuration of the steps be separated, like described by the method. The sequence is defined by itself and the steps are described only by the inputs and outputs for each step. The structure of the configuration follows the order: 1byte: features of the step。 3byte: value expected on the inputs。 5byte: value for the extra function. Table 5 shows how the user program is saved inside the controller, this is the program that describes the control of the example shown before. The sequence can be defined by 25 bytes. These bytes can be divided in five strings with 5 bytes each that define each step of the sequence (Figs. 9 and 10). 7. Conclusion The controller developed for this work (Fig. 11) shows that it is possible to create a very useful programmable controller based on microcontroller. External memories or external timers were not used in case to explore the resources that the microcontroller offers inside. Outside the microcontroller, there are only ponents to implement the outputs, inputs, analog input, display for the interface and the serial munication. Using only the internal memory, it is possible to control a pneumatic system that has a sequence with 48 steps if all the resources for all steps are used, but it is possible to reach sixty steps in the case of a simpler system. The programming of the controller does not use PLC languages, but a configuration that is simple and intuitive. With electropneumatic system, the programming follows the same technique that was used before to design the system, but here the designer work s directly with the states or steps of the system. With a very simple machine language the designer can define all the configuration of the step using four or five bytes. It depends only on his experience to use all the resources of the controller. The controller task is not to work in the same way as a mercial PLC but the purpose of it is to be an example of a versatile controller that is designed for a specific area. Because of that, it is not possible to say which one works bett
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