电气专业外文翻译---应用于电气系统的可编程序控制器-电气类(编辑修改稿)

电气专业外文翻译---应用于电气系统的可编程序控制器-电气类(编辑修改稿)内容摘要：

第 8 页 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. 第 9 页 5. Example of electropneumatic system The system is not a representation of a specific machine, but it is made with some mon movements and ponents found in a real one. The system is posed of four actuators. The actuators A, B and C are double acting and Dsingle acting. Actuator A advances 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 speed is regulated by a flowing control valve. It was the 第 10 页 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. 第 11 页 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。 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. 第 12 页 第 13 页 The auxiliary elements are included, like the automatic/manual switcher that permit a continuous work and the two start buttons that make the operator o。