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1、 1、 外文原文（復(fù)印件） A: Fundamentals of Single-chip Microcomputer The single-chip microcomputer is the culmination of both the development of the digital computer and the integrated circuit arguably the tow most significant inventions of the 20th century [1]. These tow types of architectu

2、re are found in single-chip microcomputer. Some employ the split program/data memory of the Harvard architecture, shown in Fig.3-5A-1, others follow the philosophy, widely adapted for general-purpose computers and microprocessors, of making no logical distinction between program and data memory as i

3、n the Princeton architecture, shown in Fig.3-5A-2. In general terms a single-chip microcomputer is characterized by the incorporation of all the units of a computer into a single device, as shown in Fig3-5A-3. Program memory Input& Output unit CPU Data memory

4、 Fig.3-5A-1 A Harvard type Input& Output unit CPU memory Fig.3-5A-2. A conventional Princeton computer Timer/ Counter System clock External Timing components Serial I/O ROM Rese

5、t Prarallel I/O RAM Interrupts CPU Power Fig3-5A-3. Principal features of a microcomputer Read only memory (ROM).ROM is usually for the permanent, non-volatile storage of an applications program .Many microcomputers and microcontro

6、llers are intended for high-volume applications and hence the economical manufacture of the devices requires that the contents of the program memory be committed permanently during the manufacture of chips . Clearly, this implies a rigorous approach to ROM code development since changes cannot be ma

7、de after manufacture .This development process may involve emulation using a sophisticated development system with a hardware emulation capability as well as the use of powerful software tools. Some manufacturers provide additional ROM options by including in their range devices with (or intende

8、d for use with) user programmable memory. The simplest of these is usually device which can operate in a microprocessor mode by using some of the input/output lines as an address and data bus for accessing external memory. This type of device can behave functionally as the single chip microcomputer

9、from which it is derived albeit with restricted I/O and a modified external circuit. The use of these ROMless devices is common even in production circuits where the volume does not justify the development costs of custom on-chip ROM[2];there can still be a significant saving in I/O and other chips

10、compared to a conventional microprocessor based circuit. More exact replacement for ROM devices can be obtained in the form of variants with 'piggy-back' EPROM(Erasable programmable ROM )sockets or devices with EPROM instead of ROM 。These devices are naturally more expensive than equivalent ROM devi

11、ce, but do provide complete circuit equivalents. EPROM based devices are also extremely attractive for low-volume applications where they provide the advantages of a single-chip device, in terms of on-chip I/O, etc. ,with the convenience of flexible user programmability. Random access memory (

12、RAM).RAM is for the storage of working variables and data used during program execution. The size of this memory varies with device type but it has the same characteristic width (4,8,16 bits etc.) as the processor ,Special function registers, such as stack pointer or timer register are often logical

13、ly incorporated into the RAM area. It is also common in Harard type microcomputers to treat the RAM area as a collection of register; it is unnecessary to make distinction between RAM and processor register as is done in the case of a microprocessor system since RAM and registers are not usually phy

14、sically separated in a microcomputer . Central processing unit (CPU).The CPU is much like that of any microprocessor. Many applications of microcomputers and microcontrollers involve the handling of binary-coded decimal (BCD) data (for numerical displays, for example) ,hence it is common to find th

15、at the CPU is well adapted to handling this type of data .It is also common to find good facilities for testing, setting and resetting individual bits of memory or I/O since many controller applications involve the turning on and off of single output lines or the reading the single line. These lines

16、 are readily interfaced to two-state devices such as switches, thermostats, solid-state relays, valves, motor, etc. Parallel input/output. Parallel input and output schemes vary somewhat in different microcomputer; in most a mechanism is provided to at least allow some flexibility of choosing which

17、 pins are outputs and which are inputs. This may apply to all or some of the ports. Some I/O lines are suitable for direct interfacing to, for example, fluorescent displays, or can provide sufficient current to make interfacing other components straightforward. Some devices allow an I/O port to be c

18、onfigured as a system bus to allow off-chip memory and I/O expansion. This facility is potentially useful as a product range develops, since successive enhancements may become too big for on-chip memory and it is undesirable not to build on the existing software base. Serial input/output .Serial co

19、mmunication with terminal devices is common means of providing a link using a small number of lines. This sort of communication can also be exploited for interfacing special function chips or linking several microcomputers together .Both the common asynchronous synchronous communication schemes requ

20、ire protocols that provide framing (start and stop) information .This can be implemented as a hardware facility or U(S)ART(Universal(synchronous) asynchronous receiver/transmitter) relieving the processor (and the applications programmer) of this low-level, time-consuming, detail. t is merely necess

21、ary to selected a baud-rate and possibly other options (number of stop bits, parity, etc.) and load (or read from) the serial transmitter (or receiver) buffer. Serialization of the data in the appropriate format is then handled by the hardware circuit. Timing/counter facilities. Many application of

22、 single-chip microcomputers require accurate evaluation of elapsed real time .This can be determined by careful assessment of the execution time of each branch in a program but this rapidly becomes inefficient for all but simplest programs .The preferred approach is to use timer circuit that can ind

23、ependently count precise time increments and generate an interrupt after a preset time has elapsed .This type of timer is usually arranged to be reloadable with the required count .The timer then decrements this value producing an interrupt or setting a flag when the counter reaches zero. Better tim

24、ers then have the ability to automatically reload the initial count value. This relieves the programmer of the responsibility of reloading the counter and assessing elapsed time before the timer restarted ,which otherwise wound be necessary if continuous precisely timed interrupts were required (as

25、in a clock ,for example).Sometimes associated with timer is an event counter. With this facility there is usually a special input pin ,that can drive the counter directly. Timing components. The clock circuitry of most microcomputers requires only simple timing components. If maximum performance i

26、s required,a crystal must be used to ensure the maximum clock frequency is approached but not exceeded. Many clock circuits also work with a resistor and capacitor as low-cost timing components or can be driven from an external source. This latter arrangement is useful is external synchronization of

27、 the microcomputer is required. WORDS AND TERMS culmination n.頂點(diǎn) spilt adj.分離的 volatile n. 易變的 commit v.保證 albeit conj.雖然 custom adj.定制的 variant adj.不同的 piggy-back adj.背負(fù)式的 socket n. 插座 B:PLC[1] PLCs (programmable logical controller) face ever more complex challenges these

28、days . Where once they quietly replaced relays and gave an occasional report to a corporate mainframe, they are now grouped into cells, given new job and new languages, and are forced to compete against a growing array of control products. For this year's annual PLC technology update ,we queried PLC

29、 makers on these topics and more . Programming languages Higher level PLC programming languages have been around for some time ,but lately their popularity has mushrooming. "As Raymond Leveille, vice president & general manager, Siemens Energy &Automation .inc; Programmable controls are being use

30、d for more and more sophisticated operations, languages other than ladder logic become more practical, efficient, and powerful. For example, it's very difficult to write a trigonometric function using ladder logic ."Languages gaining acceptance include Boolean, control system flowcharting, and such

31、function chart languages as Graphcet and its variation .And there's increasing interest in languages like C and BASIC. PLCs in process control Thus far, PLCs have not been used extensively for continuous process control .Will this continue? "The feeling that I've gotten," says Ken Jannotta, manger

32、, product planning, series One and Series Six product ,at GE Fanuc North America ,'is that PLCs will be used in the process industry but not necessarily for process control." Several vendors -obviously betting that the opposite will happen -have introduced PLCs optimized for process application .Ri

33、ch Ryan, manger, commercial marketing, Allen-bradley Programmable Controls Div., cites PLCs's increasing use such industries as food ,chemicals ,and petroleum. Ryan feels there are two types of applications in which they're appropriate. "one," he says," is where the size of the process control syste

34、m that's being automated doesn't justify DCS[distributed control system].With the starting price tags of chose products being relatively high, a programmable controller makes sense for small, low loop count application .The second is where you have to integrate the loop closely with the sequential l

35、ogical .Batch controllers are prime example ,where the sequence and maintaining the process variable are intertwined so closely that the benefits of having a programmable controller to do the sequential logical outweighs some of the disadvantages of not having a distributed control system." Bill Ba

36、rkovitz, president of Triconex, predicts that "all future controllers that come out in the process control system business will embrace a lot of more PLC technology and a lot more PLC functionality than they ever did before ." Communications and MAP Communications are vital to an individual automa

37、tion cell and to be automated factory as a whole. We've heard a lot about MAP in the last few years ,and a lot of companies have jumped on the bandwagon.[2]Many, however, were disappointed when a fully-defined and completed MAP specification didn't appear immediately .Says Larry Komarek: "Right now

38、, MAP is still a moving target for the manufacturers, a specification that is not final .Presently, for example. people are introducing products to meet the MAP2.1standard .Yet2.1-based products will be obsolete when the new standard for MAP3.0 is introduced." Because of this, many PLC vendors are

39、holding off on full MAP implementations. Omron, for example, has an ongoing MAP-compatibility program;[3]but Frank Newburn, vice president of Omron's Industrial Division ,reports that because of the lack of a firm definition ,Omron's PLCs don't yet talk to MAP. Since it's unlikely that an individua

40、l PLC would talk to broad MAP anyway, makers are concentrating on proprietary networks. According to Sal Provanzano, users fear that if they do get on board and vendors withdraw from MAP, they'll be the ones left holding a communications structure that's not supported. Universal I/O While there ar

41、e concerns about the lack of compatible communications between PLCs from different vendors, the connection at the other end-the I/O-is even more fragmented .With rare exceptions, I/O is still proprietary .Yet there are those who feel that I/O will eventually become more universal .GE Fanuc is hoping

42、 to do that with its Genius smart I/O line. The independent I/O makers are pulling in the same direction. Many say that I/O is such a high-value item that PLC makers will always want to keep it proprietary .As Ken Jannotta, says: "The I/O is going to be a disproportionate amount of the hardware sa

43、le. Certainly each PLC vendor is going to try to protect that. "For that reason, he says, PLC makers won't begin selling universal I/O system from other vendor. "if we start selling that kind of product, "says jannotta, "what do we manufacture?" With more intelligent I/O appearing, Sal Provanzano f

44、eels this will lead to more differentiation among I/O from different makers. "Where the I/O becomes extremely intelligent and becomes part of the system, "he says, "it really is hard to define which is the I/O and which is CPU. It really CPU, if you will, is equally integrated into the system as the

45、 I/O." Connecting PLC I/O to PCs While different PLCs probably will continue to use proprietary I/O, several vendors make it possible to connect5 their I/O to IBM PC-compatible equipment. Alle-bradeley, Could, and Cincinnati Milacron already have, and rumor has it that GE is planning something a

46、long these same lines .[4]Bill Ketelhut, manage of product planning at GE Fanuc North America ,sees this sort of thing as alternative to universal I/O."I think the trend ,instead of toward universal I/O, will be multiple host interface ," he says .Jodie Glore ,director of marking, Square D Automatio

47、n Products, Views it as another indication that PLCs are, and have been for some time, industrial computers. PLCs VS PCs If the IBM 7552, the Action Instruments BC22,and other computers are appearing on the factory floor, won't this mean new competition for PLCs? Rich Ryan: "There are some control

48、 functions that are better jobs for computers. Programmable controllers have been forced to fit into those applications. "Yet, the majority of vendors we surveyed don't like the "PC invasion" will pose a problem for them .Most said that PLCs and PCs are enough apart in architecture that they will us

49、ually do the control. They don't feel that PCs will take jobs from PLCs just because PLC I/O modules can now be connected to PCs; they believe this simply means that PLCs and PCs will be able to share the same data. "There are inherent architectural differences between a general purpose computer,"

50、says Rich Ryan, "and a programmable controller .There are hardware constructs built into almost every manufacture's programmable controller today that customize the hardware to run ladder logic and to solve machine code. "One fundamental difference he cites is called state of the machine .Ryan: "Whe

51、n you shut the machine off, or interrupt the cycle, or you jump to another spot in the cycle, programmable controllers inherently remember the state of the machine: what the timers were, what the counters were ,what the states of all the latches were .Computers don't inherently do that." WORDS A

52、ND TERMS bet v.確信 optimized n.優(yōu)化程序 corporate adj.共同的 mushroom v.迅速發(fā)展 trigonometric function 三角函數(shù) vendor n.廠商 tag n.標(biāo)簽 smart adj.智能型的 compatible adj.兼容的 2、 外文資料翻譯譯文 單片機(jī)基礎(chǔ) 單片機(jī)是電腦和集成電路發(fā)展的巔峰，有據(jù)可查的是他們也是20世紀(jì)最有意義的兩大發(fā)明。 這兩種特性在單片機(jī)中得到了充分的體現(xiàn)。一些廠家用這兩種特性區(qū)分程序內(nèi)存和數(shù)據(jù)內(nèi)存在硬件中的特性，如圖3-5A-1，依據(jù)同樣的原

53、理廣泛的適用于一般目的的電腦和微電腦，一些廠家在程序內(nèi)存和數(shù)據(jù)內(nèi)存之間不區(qū)分的像Princeton特性，展示如圖3-5A-2. 只讀存貯器(ROM). ROM是通常的永久性的，非應(yīng)用程序的易失性存儲(chǔ)器。不少微機(jī)和單片機(jī)用于大批量應(yīng)用，因此，經(jīng)濟(jì)的設(shè)備制造要求的程序存儲(chǔ)器的內(nèi)容是在制造期間永久性的刻錄在芯片中，這意味著嚴(yán)謹(jǐn)?shù)姆椒?，因?yàn)樾薷腞OM代碼不能制造之后發(fā)展。這一發(fā)展過(guò)程可能涉及仿真,使用硬件仿真功能以及強(qiáng)大的軟件工具使用先進(jìn)的開(kāi)發(fā)系統(tǒng)。 一些制造商在其提供的設(shè)備包括的范圍（或擬使用）用戶可編程內(nèi)存.其中最簡(jiǎn)單的通常是設(shè)備能夠運(yùn)行于微處理器模式通過(guò)使用一些輸入/輸出作為地址線額外的RO

54、M選項(xiàng)和數(shù)據(jù)總線訪問(wèn)外部?jī)?nèi)存.這種類(lèi)型的設(shè)備可以表現(xiàn)為單芯片微型計(jì)算機(jī)盡管有限制的I / O和外部修改這些設(shè)備的電路.小內(nèi)存裝置的應(yīng)用是非常普遍的在永久性內(nèi)存的制造中 [2];但仍然可以在我節(jié)省大量成本I/ O和其它芯片相比，傳統(tǒng)的基于微處理器電路.更準(zhǔn)確的ROM設(shè)備更換，可在與'形式變種背馱式'EPROM（可擦除可編程只讀存儲(chǔ)器）插座或存儲(chǔ)器，而不是ROM器件。這些器件自然價(jià)格比同等ROM設(shè)備貴，但不提供完整的等效電路.EPROM的設(shè)備也非常有吸引力對(duì)于低容量應(yīng)用中，他們提供的單芯片器件的優(yōu)勢(shì)，在以下方面的板載I / O等，在靈活的用戶可編程帶來(lái)的便利。 隨機(jī)存取存儲(chǔ)器（RAM

55、）。RAM用于變量和工作在程序使用該存儲(chǔ)器的執(zhí)行.隨數(shù)據(jù)存儲(chǔ)設(shè)備的大小不同類(lèi)型而有所不同，但具有相同的特征寬度（4,8,16 比特等）作為處理器。特殊功能寄存器，如棧指針或定時(shí)器寄存器，往往邏輯納入內(nèi)存區(qū)域.它也在型微電腦的硬件中做集中內(nèi)存，它是不必要的區(qū)分內(nèi)存和處理器之間的區(qū)別在通常不物理上分開(kāi)的微機(jī)中。 中央處理單元（CPU）。CPU是很象微型電子計(jì)算機(jī)和微控制器的任何微電腦.許多微電腦和微控制器涉及到二進(jìn)制編碼(十進(jìn)制處理（BCD）的數(shù)據(jù)為例）數(shù)字顯示，因而，常?？梢园l(fā)現(xiàn)該CPU是很適合處理這種類(lèi)型的數(shù)據(jù)。對(duì)設(shè)施良好與否進(jìn)行的測(cè)試，設(shè)置和重置單個(gè)位的內(nèi)存或I / O控制器的應(yīng)用程序，也

56、是常見(jiàn)的因?yàn)樵S多涉及打開(kāi)和關(guān)閉的單輸出線或在單線.這些線很容易連接到二進(jìn)制的設(shè)備，如開(kāi)關(guān)，恒溫器，固態(tài)繼電器，閥門(mén)，電機(jī)等 并行輸入/ 輸出.并行輸入和輸出的計(jì)劃有所不同，在不同的微機(jī)，在大多數(shù)設(shè)立一個(gè)機(jī)制，至少選擇讓其中一些引腳輸出，一些引腳輸如是非常靈活的。這可能適用于所有或端口.有些I / O線直接連接到適當(dāng)?shù)脑O(shè)備，例如，熒光顯示器，也可以提供足夠的電流，使接口和其他設(shè)備直接相連.一些設(shè)備允許一個(gè)I / O端口,其他組件將作為系統(tǒng)總線配置為允許片外存儲(chǔ)器和I / O擴(kuò)展。這個(gè)設(shè)施是潛在有用的一個(gè)產(chǎn)品系列的發(fā)展，因?yàn)檫B續(xù)增強(qiáng)可能成為太上存儲(chǔ)器，這是不可取的，不是建立在現(xiàn)有的軟

57、件基礎(chǔ)上的。 串行輸入/輸出。串行通信是指與終端設(shè)備的鏈接使用少量的通訊線.這種通訊也可利用特殊的接口連接功能芯片使幾個(gè)微型機(jī)連在一起。雙方共同異步同步通信方案要求的規(guī)則提供成幀（啟動(dòng)和停止）的信息。這可以作為一個(gè)硬件設(shè)施或U（擰）藝術(shù)（通用執(zhí)行（同步）異步接收器/發(fā)送器）減輕處理器（和應(yīng)用程序）的這種低層次的確費(fèi)時(shí).它也只需要選擇一個(gè)波特率及其他可能的選擇（停止位，奇偶校驗(yàn)等）和負(fù)載號(hào)碼（或讀?。?，串行發(fā)送器（或接收）的緩沖器.進(jìn)行適當(dāng)?shù)母袷降臄?shù)據(jù)串行處理，然后由硬件電路完成。 定時(shí)/計(jì)數(shù)器設(shè)施。許多應(yīng)用的單片機(jī)需要對(duì)過(guò)去的真實(shí)時(shí)間準(zhǔn)確的評(píng)價(jià)。這可以由每個(gè)程序中的執(zhí)行時(shí)間分支認(rèn)真評(píng)估

58、，但除最簡(jiǎn)單的程序外，他的工作效率不高。首選方法是使用計(jì)時(shí)器電路，能獨(dú)立計(jì)算精確的時(shí)間增量，并生成一個(gè)預(yù)設(shè)的時(shí)間后中斷的時(shí)間。這種類(lèi)型的定時(shí)器通常在所要求的數(shù)量可重載中應(yīng)用。計(jì)時(shí)器然后減少此值產(chǎn)生中斷或設(shè)置標(biāo)記時(shí)，計(jì)數(shù)器到達(dá)零.更好的計(jì)時(shí)器有自動(dòng)加載初始值的功能。這將緩解重新加載計(jì)數(shù)器和評(píng)估所用的時(shí)間，計(jì)時(shí)器重新啟動(dòng)之前這是必要的。有時(shí)候與定時(shí)器相關(guān)的是一個(gè)事件計(jì)數(shù)器。這個(gè)設(shè)備通常有一個(gè)特殊的輸入引腳，可直接驅(qū)動(dòng)計(jì)數(shù)器。 定時(shí)元件。大多數(shù)微型計(jì)算機(jī)時(shí)鐘電路只需要簡(jiǎn)單的計(jì)時(shí)元件.如果要求最高性能，必須使用晶體以確保最大時(shí)鐘頻率接近，但不會(huì)超出。許多時(shí)鐘電路，還具有電阻和低電容工作成本定時(shí)元件，

59、也可以從外部源驅(qū)動(dòng)。這后一種安排是有用的在微機(jī)外部同步是必需的時(shí)候。 B:PLC[1] 今天的PLC（可編程邏輯控制器）將面對(duì)日益復(fù)雜的挑戰(zhàn)。一旦他們悄悄地取代繼電器，偶爾向主機(jī)報(bào)告，如果他們將他們比作細(xì)胞，賦予新的工作和新的語(yǔ)言，將被迫和大量的控制產(chǎn)品競(jìng)爭(zhēng)。對(duì)于今年的年度PLC技術(shù)的更新，我們對(duì)PLC的制造商會(huì)就這些主題提出更多問(wèn)題. 編程語(yǔ)言 更高水平的PLC編程語(yǔ)言已經(jīng)推行有一段時(shí)間了，但最近的流行，如雨后春筍般。正如雷蒙德萊韋耶，副總裁兼總經(jīng)理，西門(mén)子能源和自動(dòng)化公司，可編程控制正在為更復(fù)雜的操作使用，梯形邏輯比語(yǔ)言變得更加實(shí)際，有效和強(qiáng)大的。舉例來(lái)說(shuō)，很難寫(xiě)三角函數(shù)使用梯形

60、邏輯。“語(yǔ)言為人們所接受，包括布爾，控制系統(tǒng)流程圖，這種功能圖及其變化圖表語(yǔ)言。而且有越來(lái)越多像C和BASIC語(yǔ)言的興趣?！? 在過(guò)程的PLC控制 到目前為止，PLC的沒(méi)有大量用于連續(xù)過(guò)程控制，會(huì)繼續(xù)嗎？“我感覺(jué)到了，PLC將用于過(guò)程工業(yè)，但不一定過(guò)程控制。” Jannotta說(shuō)。 幾個(gè)供應(yīng)商，顯然是把賭注押在相反會(huì)發(fā)生，已經(jīng)實(shí)行了PLC的應(yīng)用優(yōu)化的過(guò)程。富瑞安的經(jīng)理認(rèn)為PLC將越來(lái)越多地使用食品等行業(yè)，化工，石化.Ryan認(rèn)為有兩種類(lèi)型的應(yīng)用程序中，他們是合適的?！爸?，”他說(shuō)，“是其中的過(guò)程控制系統(tǒng)，目前已被沒(méi)有理由自動(dòng)化DCS的大小[分布式控制系統(tǒng)]隨著價(jià)格標(biāo)簽開(kāi)始。產(chǎn)品的選擇是比較

61、高，可編程控制器為小，低環(huán)數(shù)的應(yīng)用意義。第二種是你必須融入順序邏輯。批次控制循環(huán)密切合作是最好的例子，那里的順序和維持過(guò)程變量是交織在一起的密切合作，使擁有一個(gè)可編程控制器的邏輯順序做的好處遠(yuǎn)遠(yuǎn)超過(guò)了不具有分布式控制系統(tǒng)的一些缺點(diǎn)?！? Bill Barkovitz， Triconex的總統(tǒng)，預(yù)言：“今后所有的控制器在過(guò)程控制系統(tǒng)的業(yè)務(wù)將引用更多的PLC技術(shù)， PLC功能比以往任何時(shí)候都要多。” 通信和規(guī)范 在整體上通信是至關(guān)重要的個(gè)人自動(dòng)化單元對(duì)自動(dòng)化工廠來(lái)說(shuō)。我們聽(tīng)說(shuō)了很多規(guī)范在過(guò)去數(shù)年，許多公司都紛紛跟進(jìn)。[2]但是，不少人失望的發(fā)現(xiàn)完成地圖規(guī)范并沒(méi)有立即出現(xiàn)。拉里科馬雷克說(shuō)：“現(xiàn)在

62、，規(guī)范仍然是一個(gè)移動(dòng)目標(biāo)，規(guī)范沒(méi)有最終決定，對(duì)于制造商。目前，正在推出的產(chǎn)品樣本.人們使其產(chǎn)品滿足MAP2.1標(biāo)準(zhǔn)。然而，新標(biāo)準(zhǔn)MAP3.0被引進(jìn)時(shí)，MAP2.1為基礎(chǔ)的產(chǎn)品將被淘汰時(shí)?！? 正因?yàn)槿绱?，許多PLC廠商正在制定完整的規(guī)范. 例如Omron，擁有一個(gè)完整的兼容程序; [3]，但弗蘭克紐伯恩，副歐姆龍工業(yè)部總裁，報(bào)告說(shuō)，由于缺乏公司的定義，歐姆龍的PLC還談不上規(guī)范。 由于不太可能將個(gè)人的PLC廣泛的交談，制造商更專(zhuān)注于專(zhuān)有的網(wǎng)絡(luò).按照薩爾Provanzano說(shuō)法，用戶擔(dān)心，如果他們不從規(guī)則上和供應(yīng)商妥協(xié)，他們將要加大對(duì)通信結(jié)構(gòu)的不支持。 通用的I / O 然而大多

63、數(shù)PLC的兼容問(wèn)題不同廠商的溝通不夠，在另一端連接的I / O問(wèn)題，更是支離破碎的。除了少數(shù)例外，I / O是仍然專(zhuān)有技術(shù)。然而，誰(shuí)是那些感覺(jué)的I / O最終將成為更具有普遍性。GE Fanuc的希望這樣做與天才智能I / O線.各個(gè)獨(dú)立I / O制造商都在同一方向進(jìn)發(fā)。 許多人說(shuō)，I / O是這樣一個(gè)高價(jià)值項(xiàng)目， PLC制造商將永遠(yuǎn)希望保持它的專(zhuān)有性。由于肯Jannotta。說(shuō)：“ I / O將在硬件銷(xiāo)售中不成比例。當(dāng)然每個(gè)PLC供應(yīng)商將試圖保護(hù)這一點(diǎn)?！背鲇谶@個(gè)原因，他說(shuō)，PLC的制造商將不會(huì)開(kāi)始銷(xiāo)售通用I / O和其他廠商的系統(tǒng)。“如果我們開(kāi)始銷(xiāo)售該產(chǎn)品的實(shí)物，那我們還有什么可生產(chǎn)的？

64、” Jannotta說(shuō)道 隨著更多智能I / O出現(xiàn)，薩爾Provanzano認(rèn)為在不同的制造商中間這將導(dǎo)致更多的分化。“哪里的I / O變得非常聰明，并成為系統(tǒng)的一部分真的很難定義，哪些是I / O，哪些是CPU.隨著分布式的發(fā)展，如果你愿意，CPU也同樣可以納入作為I / O的系統(tǒng)” PLC的 I / O和個(gè)人電腦的連接 雖然不同的PLC廠商可能會(huì)繼續(xù)用專(zhuān)有的I / O，但一些廠商使I / O連接到IBM PC這樣的兼容設(shè)備成為可能.Alle - bradeley和辛辛那提米拉克龍公司已經(jīng)擁有，并有傳言說(shuō)，通用的電氣計(jì)劃將沿著同樣的思路。克特爾胡特， GE Fanuc北美的產(chǎn)品規(guī)劃

65、經(jīng)理，認(rèn)為是I/ O的普及“我想多個(gè)主機(jī)接口將代替I/O的趨勢(shì)，”他說(shuō)。朱迪格洛爾，市場(chǎng)經(jīng)理，Square D Automation Products，將PLC看做是工業(yè)電腦。 PLC VS電腦 如果IBM 7552，行動(dòng)儀器BC22，和其他計(jì)算機(jī)出現(xiàn)在工廠，這意味著不會(huì)對(duì)PLC的新的競(jìng)爭(zhēng)？富瑞安：“有一些控制功能，可用于電腦.可編程程序控制器更好的工作已被迫適應(yīng)這些應(yīng)用。“然而，在我們調(diào)查的廠商多數(shù)不認(rèn)為“個(gè)人電腦入侵”將對(duì)他們產(chǎn)生問(wèn)題。大多表示PLC和PC結(jié)構(gòu)上的差別決定他們不同的作用，PC將主管通訊和管理，PLC則進(jìn)行控制，他們相信這只是意味著，PLC和個(gè)人電腦將能夠共享相同的數(shù)據(jù)。 富瑞恩說(shuō)：“通用的計(jì)算機(jī)內(nèi)在結(jié)構(gòu)不同，可編程控制器硬件結(jié)構(gòu)有內(nèi)置到幾乎每一個(gè)制造商的可編程控制器。今天定制的硬件來(lái)運(yùn)行梯形邏輯，解決機(jī)器代碼?！痹诟镜膮^(qū)別上，他引用了一個(gè)稱呼“機(jī)器狀態(tài)”。富瑞安說(shuō)：“當(dāng)你關(guān)閉機(jī)器，或中斷周期，或者跳轉(zhuǎn)到另一個(gè)周期，現(xiàn)場(chǎng)可編程控制器本身記得機(jī)器的狀態(tài)：定時(shí)器狀態(tài)是什么，計(jì)數(shù)器狀態(tài)是什么，鎖存的狀態(tài)是什么,但計(jì)算機(jī)本身不這樣做?！? 11 教學(xué)-材料