plc 相關(guān)問題外文翻譯

1、<p><b>　　大學(xué)</b></p><p><b>　　畢業(yè)設(shè)計(jì)</b></p><p><b>　　（外文翻譯材料）</b></p><p>　　PLC Question</p><p>　　ABSTRACT: This paper describes th

2、e main components of the PLC, and attention problems in use (such as the environment in use, the use of pre-note, etc.)</p><p>　　Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is

3、usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontroller

4、s in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PL</p><p&

5、gt;　　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.

6、But, when the production environment is too bad, the electromagnetic interference is special intense, or installs uses improper, cannot guarantee PLC the normal operation, therefore should pay attention to the following

7、question in the use. </p><p>　　First, Siemens PLC maintenance </p><p>　　1, maintenance procedures, equipment, periodic testing, adjustment provisions (1) half-yearly or quarterly inspection PLC

8、 cabinet terminal connections, and if time to re-loose strong local connection; (2) of the cabinet to the host power supply voltage of the monthly re-survey work; Second, the provisions of cleaning equipment on a regul

9、ar basis (1) every six months or a quarter of the PLC to clean, cut off power to the PLC power supply to the power rack, CPU board and input / output board i</p><p>　　Second, installment and wiring</p>

10、;<p>　　(1) The power line, the pilot wire as well as the PLC power line and the I/O line should distinguish the wiring, between the insulating transformer and PLC and I/O should use the double rubberized wire conn

11、ection.</p><p>　　(2) PLC should be far away from the strong jamming source like electric welding machine, the high efficiency silicon rectifier unit and the large-scale power equipment, cannot install with t

12、he high-pressured electric appliance in the identical switch cabinet. </p><p>　　(3) The input and output of PLC are best separate the line, the switch quantity and the simulation quantity mus

13、t separate the placing. The simulation quantity signal's transmission should use the shielded wire, the shielding layer should an end or the both sides earth, and the earth resistance should be smaller than the shiel

14、ding layer resistance 1/10. </p><p>　　(4) The PLC elemental area and the expansion unit as well as functional module's ties cable should lie alone, prevents the outside signal the disturban

15、ce.</p><p>　　(5) The exchange output line and the direct-current output line do not use the identical root electric cable, the output line to be far away from the high tension line and the power line as far

16、 as possible, avoids parallel. </p><p>　　Third, I/O end wiring </p><p>　　1. Input wiring (1) inputs the wiring not to surpass 30 meters generally. But if the environment disturbance is small, wh

17、en the loss of voltage is not big, the input wiring may suitable long. </p><p>　　(2)Inputs/the output line not to be able to use the identical root electric cable, the input/output line to be separated. <

18、/p><p>　　(3)Uses the normally opened contact form to connect the input end as far as possible, causes the establishment the trapezoidal chart to be consistent with the relay schematic diagram, is advantageous f

19、or reading. </p><p>　　2. Outgoing junction </p><p>　　(1) The out-put wiring divides into the independent output and the public output. In not group, may use the different type and the voltage cl

20、ass output voltage. But can only use the identical type, the identical voltage class power source in the identical group's output. </p><p>　　(2) Because the PLC output element is sealed on the print circ

21、uit wafer, and connects to the terminal strip, if will connect output element's load short circuit, will burn down the print circuit wafer, therefore, application fuse protection output element. </p><p>

22、　　(3)Uses when the relay outputs, withstands inductive load's size, will affect relay's service life, therefore, time use inductive load the selective relay working life must be long. </p><p>　　(4) T

23、he PLC output load possibly has the disturbance, must therefore take the measure to control, if direct-current output's after flow guarantees protects, the exchange output anti- accommodates the absorbing circuit, th

24、e transistor and the bidirectional thruster output by-passed resistor protection.</p><p>　　Fourth, outside security electric circuit to guarantee that the overall system can under the secure state the reliab

25、le work, avoids, because the external power supply breaks down, PLC to present the heavy economic loss which and the person casualty exceptionally, the disoperation as well as outputs by mistake creates, PLC the outside

26、should install the essential protection circuit. </p><p>　　(1) Stops the electric circuit anxiously. Regarding can cause the user to cause the damage the dangerous load, besides performs in the control proce

27、dure to consider, but also exterior should design the emergency stop electric circuit, causes when PLC breaks down, can cause the injury load power source reliably to shut off.</p><p>　　(2)Fragment. The forw

28、ard and reverse revolution and so on reversible operation's control system must establish the exterior electric appliance interlock protection; the reciprocation moves and rises and falls motion the control system, m

29、ust establish the exterior spacing protection circuit.</p><p>　　(3)The programmable controller has self-checking functions and so on surveillance timer, when inspects exceptionally, outputs completely the cl

30、osure. But when programmable controller CPU breakdown cannot control the output, therefore, regarding can cause the user to cause the damage the dangerous load, to guarantee that the equipment moves under the secure stat

31、e, must design the external circuit to protect. </p><p>　　(4) Power source load protection. If the PLC power source breaks down, the interruption interval is short in 10 seconds, PLC works not affected, if

32、the power source interrupt surpasses 10 second or the power source drops surpasses the permissible value, then the PLC stop work, all output also separates; when the power source restores, if RUN input connection, then o

33、perates carries on automatically. Therefore, to establish the essential current limiting protection circuit to some easy over-loadin</p><p>　　(5) Significant breakdown warning and protection. Regarding easy

34、to have heavy accident'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

35、 through the external circuit, caused the control system to move under the safe condition.</p><p>　　Fifth, PLC earth the good earth is guaranteed that the PLC reliable work the important condition, may avoid

36、 the heterogametic the voltage surge harm. PLC meets the grounding and machine's ground terminal docking, meets the grounding the cross-sectional area should not to be smaller than 2mm2, the earth resistance is small

37、er than 100Ω; If must use the expansion unit, its ground point should accept after checking with the elemental area earth in the same place. In order to suppress adds in the pow</p><p>　　Sixth, the redundant

38、 system and hot backup system in profession in and so on petroleum, chemical industry, metallurgy certain systems, the request control device has the extremely high reliability. If the control system breaks down, will cr

39、eate the production suspension, the raw material massive wastes or the equipment trouble, will create the enormous economic loss to the enterprise. But depends on the enhancement control system hardware's reliability

40、 to satisfy the above request is only not en</p><p>　　(1) Redundancy control system in redundancy control system, entire PLC control system (or in system most important part, if the CPU module) of two set of

41、 identical system composition. Two CPU module use same user program multi-tasking, one is advocates CPU, another is spare CPU; advocates the CPU work, but the spare CPU output is forbidden, when advocates CPU breaks down

42、, spare CPU automatic investment movement. This cut process is controlled by the redundancy processing unit RPU, the switching </p><p>　　Hot backup system in the hot backup system, two CPU with the communica

43、tion 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 qui

44、ck, but its structure is simpler than the redundant system.</p><p>　　Under a lot of circumstances we are total to like to adopt the string to combine the conversion chip to carry on deliver, under this kind

45、of circumstance not need us to carry on to deposited the machine to establish too and complicatedly, but carry on the data exchanges through the data transmission instruction directly, but is not a very viable way in the

46、 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 can't</p><p>　　When you are reading the book, you hear someone kno

47、ck on door, you stop to start up of affair, open the door and combine 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 t

48、elephone through, return overdo come together knock on door to have a conversation, after dialogue complete, you continue again to see your book, this kind of circumstance we are called the interruption to it, it has the

49、 authorit</p><p>　　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 Cla

50、ss according to person's request. This kind of breaks off the medium interruption to also became to break off the set. The Class that certainly break off is relevant according to various resources of CPU with interna

51、l PLC, also following a heap of capacity size of also relevant fasten.</p><p>　　The contents that break off has a lot of kinds, for example the exterior break off, correspondence in of send out and accept th

52、e interruption and settle and the clock that count break off, still have the WDT to reset the interruption etc., they enriched the CPU to respond to the category while handle various business. Speak thus perhaps you can&

53、#39;t comprehend the internal structure and operation orders of the interruption completely also, we do a very small example to explain.</p><p>　　Each equipment always will not forget a button, it also is at

54、 we meet the urgent circumstance use of, which is nasty to stop the button. When we meet the Human body trouble and surprised circumstances we as long as press it, the machine stops all operations immediately, and wait f

55、or processing the over surprised empress recover the operation again. Nasty stop the internal I/ O of the internal CPU of the button conjunction PLC to connect up, be to press button an exterior to trigger signal for CP&

56、lt;/p><p>　　When we are work a work piece, giving the PLC a signal, counting PLC inner part the machine add 1 to compute us for a day of workload, a count the machine and can solve problem in brief, certainly t

57、hey also can keep the data under the condition of dropping the electricity, urging the data not to throw to lose, this is also what we hope earnestly.</p><p>　　The PLC still has the function that the high cl

58、ass counts the machine, being us while accept some dates of high speed, the high speed that here say is the data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously

59、, calculating high-speed signal of the data processor DSP etc., we will adopt the high class to count the machine to help we carry on count. It at the PLC carries out the procedure once discover that the high class count

60、s the machine</p><p>　　You heard too many this phrases perhaps:" crash", the meaning that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can&#

61、39;t result in procedure circulate. The PLC also has the similar circumstance, there is a watchdog WDT in the inner part of PLC, we can establish time that a procedure of WDT circulate, being to appear the procedure to j

62、ump to turn the mistake in the procedure movement process or the procedure is busy, movement time of the proce</p><p>　　The PLC development has already entered for network ages of correspondence from the mod

63、e of the one, and together other works control the net plank and I/ O card planks to carry on the share easily. A state software can pass all se hardwires link, more animation picture of keep the view to carries on the c

64、ontrol, and cans pass the Internet to carry on the control in the foreign land, the blast-off that is like the absolute being boat No.5 is to adopt this kind of way to make airship go up the sk</p><p>　　The

65、development of the higher layer needs our continuous effort to obtain. The PLC emergence has already affected a few persons fully, we also obtained more knowledge and precepts from the top one experience of the generatio

66、n, coming to the continuous development PLC technique, push it toward higher wave tide.</p><p>　　Knowing the available PLC network options and their best applications will ensure an efficient and flexible co

67、ntrol system design.</p><p>　　The programmable logic controller's (PLC's) ability to support a range of communication methods makes it an ideal control and data acquisition device for a wide variety

68、of industrial automation and facility control applications. However, there is some confusion because so many possibilities exist. To help eliminate this confusion, let's list what communications are available and whe

69、n they would be best applied.</p><p>　　To understand the PLC's communications versatility, let's first define the terms used in describing the various systems.</p><p>　　ASCII: This stand

70、s for "American Standard Code for Information Interchange." As shown in Fig. 1, when the letter "A" is transmitted, for instance, it's automatically coded as "65" by the sending equipmen

71、t. The receiving equipment translates the "65" back to the letter "A." Thus, different devices can communicate with each other as long as both use ASCII code.</p><p>　　ASCII module: This

72、intelligent PLC module is used for connecting PLCs to other devices also capable of communicating using ASCII code as a vehicle.</p><p>　　Bus topology: This is a linear local area network (LAN) arrangement,

73、as shown in Fig. 2A, in which individual nodes are tapped into a main communications cable at a single point and broadcast messages. These messages travel in both directions on the bus from the point of connection until

74、they are dissipated by terminators at each end of the bus.</p><p><b>　　PLC 相關(guān)問題</b></p><p>　　從結(jié)構(gòu)上分，PLC分為固定式和組合式（模塊式）兩種。固定式PLC包括CPU板、I/O板、顯示面板、內(nèi)存塊、電源等，這些元素組合成一個(gè)不可拆卸的整體。模塊式PLC包括CPU模塊、I

75、/O模塊、內(nèi)存、電源模塊、底板或機(jī)架，這些模塊可以按照一定規(guī)則組合配置。 在使用者看來，不必要詳細(xì)分析CPU的內(nèi)部電路，但對(duì)各部分的工作機(jī)制還是應(yīng)有足夠的理解。CPU的控制器控制CPU工作，由它讀取指令、解釋指令及執(zhí)行指令。但工作節(jié)奏由震蕩信號(hào)控制。運(yùn)算器用于進(jìn)行數(shù)字或邏輯運(yùn)算，在控制器指揮下工作。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。CPU速度和內(nèi)存容量是PLC的重要參數(shù)，它們決定著PLC的工作速度，

76、IO數(shù)量及軟件容量等，因此限制著控制規(guī)模。 PLC使用系統(tǒng)存儲(chǔ)器（現(xiàn)在大部分采用閃存技術(shù)了）用于過程控制系統(tǒng)。除了這個(gè)操作系統(tǒng)之外，它還包括一個(gè)由梯形圖翻譯成而進(jìn)制形式的用戶程序。快擦型存儲(chǔ)器（FLASH memory）的內(nèi)容只有在改變用戶程序的時(shí)候可以被改變。PLC控制器比快擦型存儲(chǔ)器使用得更早，EPROM存儲(chǔ)器比快擦型存儲(chǔ)器也更早，快擦型存儲(chǔ)器必須用紫外線（UV，Ultr</p><p>　　PLC是專門

77、為工業(yè)生產(chǎn)服務(wù)的控制裝置，通常不需要采取什么措施，就可以直接在工業(yè)環(huán)境中使用。但是，當(dāng)生產(chǎn)環(huán)境過于惡劣，電磁干擾特別強(qiáng)烈，或安裝使用不當(dāng)，都不能保證PLC的正常運(yùn)行，因此在使用中應(yīng)注意以下問題</p><p>　　一、西門子PLC保養(yǎng)</p><p>　　1、 保養(yǎng)規(guī)程、設(shè)備定期測(cè)試、調(diào)整規(guī)定 </p><p>　?。?） 每半年或季度檢查PLC柜中接線端子的連接情

78、況，若發(fā)現(xiàn)松動(dòng)的地方及時(shí)重新堅(jiān)固連接； </p><p>　?。?） 對(duì)柜中給主機(jī)供電的電源每月重新測(cè)量工作電壓； </p><p>　　2、 設(shè)備定期清掃的規(guī)定 </p><p>　　（1） 每六個(gè)月或季度對(duì)PLC進(jìn)行清掃，切斷給PLC供電的電源把電源機(jī)架、CPU主板及輸入/輸出板依次拆下，進(jìn)行吹掃、清掃后再依次原位安裝好，將全部連接恢復(fù)后送電并啟動(dòng)PLC主機(jī)。認(rèn)

79、真清掃PLC箱內(nèi)衛(wèi)生； </p><p>　?。?） 每三個(gè)月更換電源機(jī)架下方過濾網(wǎng)； </p><p>　　3、 檢修前準(zhǔn)備、檢修規(guī)程 </p><p>　?。?） 檢修前準(zhǔn)備好工具； </p><p>　　（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； </p><p>　?。?/p>

80、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； </p><p>　　4、 設(shè)備拆裝順序及方法 </p><p>　　（1） 停機(jī)檢修，必須兩個(gè)人以上監(jiān)護(hù)操作； </p><p>　　（2） 把CPU前面板上的方式選擇開關(guān)從“運(yùn)行”轉(zhuǎn)到“?！蔽恢茫?</p><p>　?。?） 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

81、； </p><p>　?。?） 把與電源架相連的電源線記清線號(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； </p><p>　?。?） CPU主板及I/0板可在旋轉(zhuǎn)模板下方的螺絲后拆下； </p><p>　?。?） 安裝時(shí)以相反順序進(jìn)行； </p><p>　　5、 檢修工藝及技術(shù)要求 </p>

82、<p>　?。?） 測(cè)量電壓時(shí)，要用數(shù)字電壓表或精度為1%的萬能表測(cè)量 </p><p>　?。?） 電源機(jī)架，CPU主板都只能在主電源切斷時(shí)取下； </p><p>　?。?） 在RAM模塊從CPU取下或插入CPU之前，要斷開PC的電源，這樣才能保證數(shù)據(jù)不混亂； </p><p>　?。?） 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

83、障燈亮?xí)r取下模塊PAM內(nèi)容將丟失； </p><p>　?。?） 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； </p><p>　?。?） 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</p><p>　　（7） 更換元件不得帶電操作； </p><p&g

84、t;　?。?） 檢修后模板安裝一定要安插到位</p><p>　　二、安裝與布線　　1、 動(dòng)力線、控制線以及PLC的電源線和I/O線應(yīng)分別配線，隔離變壓器與PLC和I/O之間應(yīng)采用雙膠線連接?！　?、 PLC應(yīng)遠(yuǎn)離強(qiáng)干擾源如電焊機(jī)、大功率硅整流裝置和大型動(dòng)力設(shè)備，不能與高壓電器安裝在同一個(gè)開關(guān)柜內(nèi)。　　3、 PLC的輸入與輸出最好分開走線，開關(guān)量與模擬量也要分開敷設(shè)。模擬量信號(hào)的傳送應(yīng)采用屏蔽線，屏蔽層應(yīng)一

85、端或兩端接地，接地電阻應(yīng)小于屏蔽層電阻的1/10。　　4、 PLC基本單元與擴(kuò)展單元以及功能模塊的連接線纜應(yīng)單獨(dú)敷設(shè)，以防止外界信號(hào)的干擾?！　?、 交流輸出線和直流輸出線不要用同一根電纜，輸出線應(yīng)盡量遠(yuǎn)離高壓線和動(dòng)力線，避免并行。三、I/O端的接線　　1、 輸入接線　?。?）輸入接線一般不要超過30米。但如果環(huán)境干擾較小，電壓降不大時(shí)，輸入接線可適當(dāng)長(zhǎng)些。（2）輸入/輸出線不能用同一根電纜，輸入/輸出線要分開。（3）盡可能采

86、用常開觸點(diǎn)形式連接到輸入端，使編制的梯形圖與繼電器原理圖一致，便于閱讀?！?． 輸出連接　?。?）輸出端接線分為獨(dú)立輸出和公共輸出。在不同組中，可采用不同類型和電壓等級(jí)的輸出電壓。但在同一組中的輸出只能用同</p><p>　　很多的情況下我們總喜歡采用串并轉(zhuǎn)換芯片來進(jìn)行傳輸，這種情況下不需要我們進(jìn)行過于復(fù)雜的寄存器設(shè)置了，而直接通過數(shù)據(jù)傳送指令進(jìn)行數(shù)據(jù)交流，但在通信中并不是一個(gè)十分可行的辦法，因?yàn)樵诎l(fā)送數(shù)據(jù)

87、的時(shí)候?qū)Ψ降腜LC必須一直等待你的數(shù)據(jù)輸出，它不能去做其他的工作。</p><p>　　當(dāng)你在看書的時(shí)候，你聽到有人敲門、你停下手上的事情、去打開門、并同敲門者對(duì)話、這個(gè)時(shí)候電話響了、你示意接個(gè)電話、在接完電話后、回過頭來同敲門者繼續(xù)對(duì)話、對(duì)話完畢后、你再繼續(xù)看你的書，這種情況我們把它稱為中斷，它具有權(quán)威性，也具有優(yōu)先性，PLC具備了這樣的功能。它的特點(diǎn)在于我們?cè)谠O(shè)備的操作過程中可能會(huì)遇到緊急的突發(fā)事件，我們要立

88、刻的停下手上的工作，去處理更重要的事情，這種情況是我們經(jīng)常所遇到的，PLC在去執(zhí)行緊急的任務(wù)時(shí)，總會(huì)先保存目前的狀態(tài)，比如程序的地址，CPU的累加器數(shù)據(jù)等，就像我們?nèi)ラ_門時(shí)要記下我們看的書在第幾頁了或者干脆作個(gè)記號(hào)，因?yàn)槲覀兇龝?huì)還要繼續(xù)接著看后面的書。CPU總是按照我們的意愿去做應(yīng)該做的事情，但你錯(cuò)誤的給它一件事情，它也會(huì)同樣的去做，這一點(diǎn)我們必須注意。</p><p>　　中斷并不是只有一個(gè)，有時(shí)會(huì)同時(shí)存在幾個(gè)

89、中斷，中斷具有優(yōu)先的級(jí)別，他們會(huì)根據(jù)人的要求去執(zhí)行更高級(jí)別的中斷。這種中斷中的中斷也就形成了中斷嵌套。當(dāng)然中斷的級(jí)別根據(jù)各種PLC內(nèi)部CPU的資源有關(guān)，同時(shí)也跟堆棧的容量大小也有關(guān)系。</p><p>　　中斷的內(nèi)容有很多種，比如外部中斷、通信中的發(fā)送和接受中斷、定時(shí)和計(jì)數(shù)的時(shí)鐘中斷、還有WDT復(fù)位中斷等，它們豐富了CPU在處理各種事務(wù)時(shí)響應(yīng)種類。這樣講也許你并不能完全理解中斷的內(nèi)部結(jié)構(gòu)和操作順序，我們做一個(gè)小小

90、的例子來說明.</p><p>　　每一個(gè)設(shè)備總是不會(huì)忘記有一個(gè)按鈕，它也是在我們遇到緊急情況時(shí)使用的，那就是急停按鈕。當(dāng)我們遇到人身事故和意外情況時(shí)我們只要按下它，機(jī)器立即停止所有的操作，并等待處理完意外后再恢復(fù)操作。急停按鈕連接PLC內(nèi)部CPU的內(nèi)部I/O接口上，當(dāng)按鈕給CPU一個(gè)外部觸發(fā)信號(hào)時(shí)，CPU對(duì)I/O進(jìn)行再次檢測(cè)，當(dāng)確認(rèn)有外部觸發(fā)信號(hào)時(shí)，CPU保護(hù)現(xiàn)場(chǎng)并將程序計(jì)數(shù)器自動(dòng)轉(zhuǎn)到相應(yīng)的外部I/O中斷程序中

91、去，當(dāng)外部中斷程序處理完畢，程序計(jì)數(shù)器返回到主程序繼續(xù)工作。有一點(diǎn)可以說明的是我們一般會(huì)把急停按鈕的外部中斷升至最高級(jí)別，從而保證安全。</p><p>　　當(dāng)我們?cè)诠ぷ魍暌粋€(gè)工件時(shí)，給PLC一個(gè)信號(hào)，將PLC的內(nèi)部計(jì)數(shù)器加1來計(jì)算我們一天的工作量時(shí)，一個(gè)簡(jiǎn)單的計(jì)數(shù)器能解決問題，當(dāng)然它們也能夠在掉電的情況下保持?jǐn)?shù)據(jù)，促使數(shù)據(jù)不丟失，這也是我們所渴望的。</p><p>　　PLC還具有高級(jí)

92、計(jì)數(shù)器的功能，當(dāng)我們?cè)诮邮芤恍└咚俚臄?shù)據(jù)時(shí)，這里所說的高速是在在微秒級(jí)的數(shù)據(jù)，比如條碼掃描機(jī)在不斷的掃描數(shù)據(jù)，數(shù)據(jù)處理器DSP計(jì)算的高速信號(hào)等，我們就要采用到高級(jí)計(jì)數(shù)器來幫助我們進(jìn)行計(jì)數(shù)。它在PLC執(zhí)行程序時(shí)一旦發(fā)現(xiàn)高級(jí)計(jì)數(shù)器對(duì)應(yīng)的中斷，就會(huì)立即放下手上的工作。經(jīng)過再次編程的梯形圖程序說明我們?cè)趫?zhí)行程序時(shí)高級(jí)計(jì)數(shù)器會(huì)自動(dòng)的執(zhí)行對(duì)應(yīng)的工作，從而將高級(jí)計(jì)數(shù)器的級(jí)別升至高一級(jí)別。</p><p>　　你也許聽過太多的這

93、個(gè)詞:“死機(jī)”，大致的意思是CPU工作量過大，內(nèi)部資源不足等情況造成程序無法運(yùn)行。PLC也有類似的情況，在PLC內(nèi)部有一個(gè)看門狗WDT，我們可以設(shè)置WDT一個(gè)程序運(yùn)行的時(shí)間，當(dāng)程序運(yùn)行過程中出現(xiàn)程序跳轉(zhuǎn)錯(cuò)誤時(shí)或者程序繁忙時(shí)，程序的運(yùn)行時(shí)間超過WDT的設(shè)置時(shí)間，CPU轉(zhuǎn)而WDT復(fù)位狀態(tài)。程序重新開始運(yùn)行，但對(duì)中斷不會(huì)進(jìn)行破壞。</p><p>　　PLC的發(fā)展已經(jīng)從單一的模式進(jìn)入了通信的網(wǎng)絡(luò)時(shí)代，并同其它的工控網(wǎng)板

94、和I/O卡板輕易的進(jìn)行共享。組態(tài)軟件可以將所有的這些硬件連接起來，通過更直觀的動(dòng)畫圖片來進(jìn)行控制，并可以通過互聯(lián)網(wǎng)在異地進(jìn)行控制，像神舟五號(hào)的發(fā)射就是采用這種辦法來使飛船升空。</p><p>　　更高層次的發(fā)展需要我們不斷的努力來取得。PLC的出現(xiàn)已經(jīng)足足影響了幾代人，我們也從上一輩的經(jīng)驗(yàn)中獲取了更多的知識(shí)和教訓(xùn)，來不斷的發(fā)展PLC技術(shù)，將它推向更高浪潮。</p><p>　　了解可用的

95、PLC網(wǎng)絡(luò)的最佳選擇，其應(yīng)用將確保有效率和靈活的控制系統(tǒng)設(shè)計(jì)?？删幊踢壿嬁刂破鳎≒LC的）能夠支持多種通信方法的范圍，使之成為一個(gè)理想的控制和工業(yè)自動(dòng)化和控制應(yīng)用各種設(shè)施數(shù)據(jù)采集裝置。然而，有一些混亂，因?yàn)檫@么多的可能性存在。為了幫助消除這種混亂，讓我們的通訊名單，可什么時(shí)候他們會(huì)是最好的應(yīng)用。</p><p>　　CPU：這代表“中央處理單元”，這其實(shí)就是一臺(tái)計(jì)算機(jī)，可編程控制器，智能設(shè)備或其他地方的算術(shù)和邏輯

96、運(yùn)算的執(zhí)行和指令被解碼和執(zhí)行的一部分。</p><p>　　菊花鏈：這是對(duì)單個(gè)設(shè)備中的PLC網(wǎng)絡(luò)，連接描述在那里，每個(gè)設(shè)備連接到下一個(gè)和通信信號(hào)從一個(gè)單位傳遞到下一個(gè)順序的方式。</p><p>　　分布式控制：這是一個(gè)自動(dòng)化的概念，即一個(gè)自動(dòng)化系統(tǒng)的部分是由單獨(dú)的控制器，這是在位于其附近地區(qū)的直接控制（控制分散控制系統(tǒng)及遍布出）。</p><p>　　為了了解PL

97、C的通信多功能性，讓我們首先定義描述的各種制度的用語：</p><p>　　ASCII碼：這代表著信息交換。1，當(dāng)字母“A”是傳播，例如，它會(huì)自動(dòng)編碼為“65由發(fā)送設(shè)備”。接收設(shè)備轉(zhuǎn)換的“65”回答。因此，不同的設(shè)備可以相互通信既是使用ASCII代碼的其他長(zhǎng)。</p><p>　　ASCII的模塊：這個(gè)智能PLC模塊是用于連接到PLC的通信也使用ASCII碼作為車輛等設(shè)備的能力。</