【正文】 接地點應盡可能靠近 PLC。（ 4）電源過負荷的防護。（ 4） PLC 的輸出負載可能產(chǎn)生干擾，因此要采取措施加以控制，如直流輸出的續(xù)流管保護，交流輸出的阻容吸收電路，晶體管及雙向晶閘管輸出的旁路電阻保護。但如果環(huán)境干擾較小，電壓降不大時，輸入接線可適當長些。但是，當生產(chǎn)環(huán)境過于惡劣，電磁干擾特別強烈，或安裝使用不當，都不能保證 PLC 的正常運行，因此在使用中應注意以下問題 一、西門子 PLC 保養(yǎng) 保養(yǎng)規(guī)程、設備定期測試、調(diào)整規(guī)定 （ 1） 每半年或季度檢查 PLC柜中接線端子的連接情況，若發(fā)現(xiàn)松動的地方及時重新堅固連接； （ 2） 對柜中給主機供電的電源每月重新測量工作電壓； 設備定期清掃的規(guī)定 （ 1） 每 六個月或季度對 PLC進行清掃，切斷給 PLC 供電的電源把電源機架、 CPU主板及輸入 /輸出板依次拆下，進行吹掃、清掃后再依次原位安裝好，將全部連接恢復后送電并啟動 PLC主機。在有些 PLC 控制器上，你可以看見作為獨立模塊的電源。程序員可以添加標記，書日和輸出設備名稱，以及對于查找錯誤或者對于系統(tǒng)維護很有用的注釋。實際上，這意味著，如果你有編程所需要的軟件，早期 PLC 控制器可以通過計算機進行編程。在應用程序開發(fā)中，通過一個串行電纜可以對程序存儲器進行重新編程。運算器用于進 行數(shù)字或邏輯運算，在控制器指揮下工作。s munications versatility, let39。s cut is also pletes by RPU. Hot backup system in the hot backup system, two CPU with the munication connection connects in together, which is at circular telegram condition .When the system presents the breakdown, advocates CPU informs spare CPU to make the spare CPU work. This cut process is not too generally quick, but its structure is simpler than the redundant system. Under a lot of circumstances we are total to like to adopt the string to bine the conversion chip to carry on deliver, under this kind of circumstance not need us 外文翻譯（ 原文 ） 9 to carry on to deposited the machine to establish too and plicatedly, but carry on the data exchanges through the data transmission instruction directly, but is not a very viable way in the correspondence, because the PLC of the other party must has been wait for your data exportation at the time of sending out the data, it can39。s input device. (5) Significant breakdown warning and protection. Regarding easy to have heavy accident39。s output. (2) Because the PLC output element is sealed on the print circuit wafer, and connects to the terminal strip, if will connect output element39。s power supply, so as to ensure the data is not confused。 4, equipment and method of disassembly sequence (1) downtime, must be two or more monitoring operation。 大學 畢業(yè)設計 （ 外文翻譯材料 ） 學 院 ： 專 業(yè) ： 學生姓名 ： 指導教師 ： 電氣與電子工程學院 電氣工程及其自動化 外文翻譯（ 原文 ） 1 PLC Question ABSTRACT: This paper describes the main ponents of the PLC, and attention problems in use (such as the environment in use, the use of prenote, etc.) Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8bit microcontrollers such as 8051, and now these are 16and 32bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of munication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output. PLC controllers have plex routines for memory checkup in order to ensure that PLC memory was not damaged (memory checkup is done for safety reasons).Generally speaking, CPU unit makes a great number of checkups of the PLC controller itself so eventual errors would be discovered early. You can simply look at any PLC controller and see that there are several indicators in the form. of light diodes for error signalization. System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating system it also contains a user program translated forma ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done through a serial cable in a program for application development. User memory is divided into blocks having special functions. Some parts of a memory are used for storing input and output status. The real status of an input is stored either as “1”or as “0”in a specific memory bit/ each input or output has one corresponding bit in memory. Other parts of memory are 外文翻譯（ 原文 ） 2 used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part of the memory. PLC controller can be reprogrammed through a puter (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed through a puter if you have the software needed for programming. Today’s transmission puters are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is corrected, it is also important to read the right program into a PLC again. It is also good to check from time to time whether program in a PLC has not changed. This helps to avoid hazardous situations in factory rooms (some automakers have established munication works which regularly check programs in PLC controllers to ensure execution only of good programs). Almost every program for programming a PLC controller possesses various useful options such as: forced switching on and off of the system input/outputs (I/O lines), program follow up in real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programmer can add remarks, names of input or output devices, and ments that can be useful when finding errors, or with system maintenance. Adding ments and remarks enables any technician (and not just a person who developed the system) to understand a ladder diagram right away. Comments and remarks can even quote precise