電氣專業(yè)外文翻譯---應(yīng)用于電氣系統(tǒng)的可編程序控制器-電氣類-文庫(kù)吧資料
2025-05-21 20:29本頁(yè)面
【正文】 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. 第 12 頁(yè) 第 13 頁(yè) 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 第 14 頁(yè) 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 第 15 頁(yè) 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。 function available on the main program for didactic purposes, the user gives the signal to execute the step. ?LCD display, which shows the status of the system, values of inputs, outputs, timer and statistics of the sequence execution. ?Beep to give important alerts, stop, start and emergency. ? Leds to show power on and others to show the state of inputs and outputs. . Security To make the final application works property, a correct configuration to execute the steps in the right way is needed, but more then that it must offer solutions in case of bad functioning or problems in the execution of the sequence. The controller 第 8 頁(yè) offers the possibility to configure two internal virtual circuits that work in parallel to the principal. These two circuits can be used as emergency or reset buttons and can return the system to a certain state at any time [2]. There are two inputs that work with interruption to get an immediate access to these functions. It is possible to configure the position, the buttons and the value of timeout of the system. . User interface The sequence of strings can be programmed using the interface elements of the controller. A Computer interface can also be used to generate the user program easily. With a good documentation the final user can use the interface to configure the strings of bytes that define the steps of the sequence. But it is possible to create a program with visual resources that works as a translator to the user, it changes his work to the values that the controller understands. To implement the munication between the puter interface and the controller a simple protocol with check sum and number of bytes is the minimum requirements to guarantee the integrity of the data. . Firmware The main loop works by reading the strings of the steps from the EEPROM memory that has all the information about the steps. In each step, the status of the system is saved on the memory and it is shown on the display too. Depending of the user configuration, it can use the interruption to work with the emergency circuit or timeout to keep the system safety. In ,a block diagram of micro controller main program is presented.
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