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Together are enough to describe correctly all the sequence. With them is possible to design the whole control circuit with the necessary logic components.But till this time,it is not a complete 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,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 show the result of using the method without the controller.Theese 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 two start buttons that make the qperator of a machine use their two hands to start the process,reducing the ridk of accidents.
6.Changing the example to a user program
In the previous chapter ,the electro-pneumatic 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 conteoller ,the control becomes easier and the complexity can be increase also.
With the time diagram,the step sequence and the elements of the system described in Table it is possible to 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.
shows how the user program is saved inside the controller, this is the program that describes the control of the exanple shown before.
The sequence can be defined by 25 bytes these bytes can be pded in five strings with 5 bytes each that define each step of the sequence.
7.conclusion
The controller developed for this work ，shows that it is possible to create a very useful programmable controller based on microcontroller. External memories that the miscrocontroller offers inside Outside the microcotroller , there ara only components to implement the outputs , inputs , analoginputs , display for the interface and the serial communication.
Using only the internal memory , it is possbel to control a pneumatic system that has a sequence with 48 stsps if all the resources for all steps ara used , but it is possble to reach sixty steps in the case of a simpler system . The programming of the controller dose not use PLC languages , but a configuration that is simple and intuitive , With electro-pneumatic system , the programming follows the same technique that was used before to design the system , but here the designer workes 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 commercial 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 better ;the system made with microcontroller is an alternative that works in a simple way.
应用于电气系统的可编程序控制器
摘要
此项目主要是研究电气系统以及简单有效的控制气流发动机的程序和气流系统的状态。它的实践基础包括基于气流的专有控制器、自动化设计、气流系统的控制程序和基于微控制器的电子设计。