【正文】 ly part numbers if replacements would be needed. This would speed up a repair of any problems that e up due to bad parts. The old way was such that a person who developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctly documented ladder diagram allows any technician to understand thoroughly how system functions. Electrical supply is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220 VAC. On some PLC controllers you’ll find electrical supply as a separate module. Those are usually bigger PLC controllers, while small and medium series already contain the supply module. User has to determine how 外文翻譯（ 原文 ） 3 much current to take from I/O module to ensure that electrical supply provides appropriate amount of current. Different types of modules use different amounts of electrical current. This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs because then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs with voltage from a small supply source already incorporated into a PLC. PLC which should pay attention in the application is specially the control device which serves for the industrial production, usually does not need to take any measure, may use directly in the industry environment. But, when the production environment is too bad, the electromagic interference is special intense, or installs uses improper, cannot guarantee PLC the normal operation, therefore should pay attention to the following question in the use. First, Siemens PLC maintenance 1, maintenance procedures, equipment, periodic testing, adjustment provisions (1) halfyearly or quarterly inspection PLC cabi terminal connections, and if time to reloose strong local connection。 (2) the way the CPU on the front panel select switch from the Run to stop position。 (4) before removing RAM modules, check the battery module is working correctly, if the battery fault light is removed when the PAM module content will be lost。s load short circuit, will burn down the print circuit wafer, therefore, application fuse protection output element. (3)Uses when the relay outputs, withstands inductive load39。s place, to guarantee the control system when the heavy accident occurs still the reliable warning and the protection, should have with the significant breakdown the contacting signal to output through the external circuit, caused the control system to move under the safe condition. Fifth, PLC earth the good earth is guaranteed that the PLC reliable work the important condition, may avoid the heterogametic the voltage surge harm. PLC meets the grounding and machine39。t do other works. When you are reading the book, you hear someone knock on door, you stop to start up of affair, open the door and bine to continue with the one who knock on door a dialogue, the telephone of this time rang, you signal hint to connect a telephone, after connecting the telephone through, return overdo e together knock on door to have a conversation, after dialogue plete, you continue again to see your book, this kind of circumstance we are called the interruption to it, it has the authority, also having sex of have the initiative, the PLC had such function .Its characteristics lie in us and may meet the urgently abrupt affairs in the operation process of the equipments, we want to stop to start immediately up of work, the whereabouts manages the more important affair, this kind of circumstance is we usually meet of, PLC while carry out urgent mission, total will keep the current appearance first, for example the address of the procedure, CPU of tired add the machine data etc., be like to stick down which the book that we see is when we open the door the page or simply make a mark, because we treat and would still need to continue immediately after book of see the behind. The CPU always does the affair that should do according to our will, but your mistake of give it an affair, it also would be same to do, this we must notice. The interruption is not only a, sometimes existing jointly with the hour several inside break, break off to have the preferred Class, they will carry out the interruption of the higher Class according to person39。s first define the terms used in describing the various systems. ASCII: This stands for American Standard Code for Information Interchange. As shown in Fig. 1, when the letter A is transmitted, for instance, it39。寄存器參與運(yùn)算，并存儲(chǔ)運(yùn)算的中間結(jié)果，它也是在控制器指揮下工作。 用戶(hù)存儲(chǔ)器被分成具有特殊功能的塊。今天的傳輸計(jì)算機(jī)是工廠(chǎng)自己對(duì) PLC 控制器進(jìn)行重新編程的理想設(shè)備。添加注釋和標(biāo)記可以使技術(shù)人員（不僅僅是開(kāi)發(fā)人員）很快理解梯形圖。用戶(hù)必須確定從 I/O 模塊取出多大電流來(lái)保證電源提供適當(dāng)?shù)碾娏?。認(rèn)真清掃 PLC 箱內(nèi)衛(wèi)生； 外文翻譯（譯文） 15 （ 2） 每三個(gè)月更換電源機(jī)架下方過(guò)濾網(wǎng)； 檢修前準(zhǔn)備、檢修規(guī)程 （ 1） 檢修前準(zhǔn)備好工具； （ 2） 為保障元件的功能不出故障及模板不損壞，必須用保護(hù)裝置及認(rèn)真作防靜電準(zhǔn)備工作； （ 3） 檢修前與調(diào)度和操作工聯(lián)系好，需掛檢修牌處掛好檢修牌； 設(shè)備拆裝順序及方法 （ 1） 停機(jī)檢修，必須兩個(gè)人以 上監(jiān)護(hù)操作； （ 2） 把 CPU前面板上的方式選擇開(kāi)關(guān)從“運(yùn)行”轉(zhuǎn)到“?！蔽恢?； （ 3） 關(guān)閉 PLC 供電的總電源，然后關(guān)閉其它給模坂供電的電源； （ 4） 把與電源架相連的電源線(xiàn)記清線(xiàn)號(hào)及連接位置后拆下，然后拆下電源機(jī)架與機(jī)柜相連的螺絲，電源機(jī)架就可拆下； （ 5） CPU 主板及 I/0 板可在旋轉(zhuǎn)模板下方的螺絲后拆下； （ 6） 安裝時(shí)以相反順序進(jìn)行； 檢修工藝及技術(shù)要求 （ 1） 測(cè)量電壓時(shí)，要用數(shù)字電壓表或精度為 1%的萬(wàn)能表測(cè)量 （ 2） 電源機(jī)架， CPU 主板都只能在主電源切斷時(shí)取下； （ 3） 在 RAM 模塊從 CPU 取下或插入 CPU 之前，要斷開(kāi) PC 的電源，這樣才能保證數(shù)據(jù)不混亂； （ 4） 在取下 RAM模塊之前，檢查一下模塊電池是否正常工作，如果電池故障燈亮?xí)r取下模塊 PAM 內(nèi)容將丟失； （ 5） 輸入 /輸出板取下前也應(yīng)先關(guān)掉總電源，但如果生產(chǎn)需要時(shí) I/0板也可在可編程控制器運(yùn)行時(shí)取下，但 CPU 板上的 QVZ（超時(shí)）燈亮； （ 6） 撥插模板時(shí)，要格外小心，輕拿輕放，并運(yùn)離產(chǎn)生靜電的物品 外文翻譯（譯文） 16 （ 7） 更換元件不得帶電操作； （ 8） 檢修后模板安裝一定要安插到位 二、安裝與布線(xiàn) 動(dòng)力線(xiàn)、控制線(xiàn)以 及 PLC 的電源線(xiàn)和 I/O 線(xiàn)應(yīng)分別配線(xiàn)，隔離變壓器與 PLC 和 I/O 之間應(yīng)采用雙膠線(xiàn)連接。