外文翻譯--plc控制系統(tǒng)設計的要點

1、<p><b>　　英文原文</b></p><p>　　Plc control system design elements</p><p>　　Submitted: ---; Accepted: March 27, 2002; Published: September 25, 2002</p><p>　　Pavan K. Hed

2、a 1 , Kapiamba Muteba 2 and Larry L. Augsburger 2</p><p>　　1 Personal Products Company, Division of McNeil-PPC, Skillman, NJ 08558</p><p>　　2 Department of Pharmaceutical Sciences, University of

3、 Maryland, School of Pharmacy, Baltimore, MD 21201</p><p><b>　　ABSTRACT</b></p><p>　　Originally, the PLC was represented by the acronym PC. There was some confusion with using this a

4、cronym as it is commonly accepted to represent personal computer. Therefore, PLC is now commonly accepted to mean programmable logic contoller.</p><p>　　A PLC is a user-friendly, microprocessor-based specia

5、lized computer that carries out control functions of many types and leves of complexity. Its purpose is to monitor crucial process parameters and adjust process operations accordingly. It can be programmed, controlled, a

6、nd operated by a person unskilled in operating computer. Essentially, a PLC’s operator draws the lines and devices of ladder diagrams with a keyboard onto a display screen. The resulting drawing is converted into compute

7、r mach</p><p>　　The computer takes the place of much of the external wiring required for control of a process. The PLC will operate any system that has output devices that go on and off (known as discrete, o

8、r digital, outputs). It can also operate any system with variable (analog) outputs. The PLC can be operated on the input side by on-off devices (discrete, or digital) or by variable (analog) input devices.</p><

9、;p>　　KEYWORDS: PLC, programmable logic contoller.</p><p>　　In the automated control domain, PLC is one kind of important control device. At present, in the world has more than 200 factories to produce mor

10、e than 300 varieties PLC product, applies in the automobile (23%), the grain processing (16.4%), chemistry/drugs manufacture (14.6%), the metal/mine (11.5%), the paper pulp/papermaking (11.3%) and so on the profession. I

11、n order to make fellow beginners conveniently to understand PLC, this article to the PLC development, the basic structure, the disposit</p><p>　　First, PLC development course</p><p>　　In the ind

12、ustrial production process, the massive switches quantity sequential control, it carries on the smooth movement according to the logical condition, and defers to the logical relations to carry on the chain-like protectio

13、n movement the control, and massive data acquisition. In the tradition, these functions are realize through air operated or the electricity control system. In 1968 American GM (general automobile) the company proposed th

14、e substitution continues the electricity control d</p><p>　　After the personal computer (is called PC) to develop, in order to be convenient, also in order to reflect the programmable controller the function

15、 characteristic, the programmable foreword controller chooses a name is Programmable Logic Controller (PLC), now, still frequently was called PLC PC. </p><p>　　The PLC definition has many kinds. The internat

16、ional electrician committee (IEC) to PLC the definition is: The programmable controller is one kind of digital operation operation electronic system, specially for applies under the industry environment designs[3]. It us

17、es the programmable foreword the memory, uses for to carry out the logic operation, the sequential control in its internal storage, fixed time, counts with operation the and so on arithmetic operation instruction, and th

18、rough digital</p><p>　　On the century 80's to the 90's intermediate stages, are PLC develop the quickest time, the yearly rate continuously maintenance are 30-40%. In this time, PLC in the processing

19、 simulation quantity ability, the digital operation ability, the man-machine connection ability and the networking capability obtains the large scale enhancement, PLC gradually enters the process control domain, substitu

20、ted in certain applications has been at the dominant position in the process control domain the DCS syst</p><p>　　PLC has the versatility strongly, the easy to operate, the adaption surface broad, the reliab

21、ility high, the antijamming ability strong, the programming is simple and so on the characteristic. PLC in the industrial automation control specially is in the sequential control status, in future which may foresee, is

22、unable to substitute.</p><p>　　Second, PLC constitution</p><p>　　From the structure the minute, PLC divides into the stationary type and the combined type (module type) two kinds. Stationary PLC

23、 including the CPU board, the I/O board, demonstrated the kneading board, the memory block, the power source and so on, these element groups synthesize a not dismantable whole. Module type PLC including the CPU module, t

24、he I/O module, the memory, the power source module, the ledger wall or the rack, these modules may defer to the certain rule combination disposition. S</p><p>　　Third, CPU constitution</p><p>　　

25、CPU is the PLC core, plays nerve center's role, every time wraps PLC at least to have CPU, it function receive and storage user program and data which entrusts with according to the PLC system program, with scanning

26、way gathering the condition or the data which sends by the scene input device, and stores the stipulation in the register, simultaneously, diagnoses the power source and in the PLC internal circuit active status and the

27、programming process grammatical error and so on. After enters th</p><p>　　CPU mainly by the logic unit, the controller, the register and realizes the data, the control and the condition main line constitutio

28、n which between them relates, the CPU unit also includes the periphery chip, the main line connection and the related electric circuit. The memory mainly uses in the stored routine and the data, is the PLC essential comp

29、osition unit.</p><p>　　Looked like in the user, nonessential multianalysis CPU internal circuit, but or should have the enough understanding to each part of work mechanism. The CPU controller controls the CP

30、U work, reads by it takes the instruction, the interpretive order and carries out the instruction. But the work rhythm by shakes the signal control. The logic unit uses in to carry on the numeral or the logic operation,

31、works under the controller direction. The register participation operation, coexists stores the </p><p>　　The CPU speed and the memory capacity are the PLC important parameter, they are deciding the PLC work

32、ing speed, the IO quantity and the software capacity and so on, therefore is limiting the control scale.</p><p>　　Fourth, I/O module</p><p>　　PLC and the electrical return route connection, is (

33、I/O) completes through the input output unit. The I/O module integrated the PLC I/O electric circuit, its input temporary storage device reflection input signal condition, output point reflection output latch condition.

34、The load module transforms the electrical signal the digital signal to enter the PLC system, the output module is opposite. I/O divides into the switch quantity input (DI), switch quantity output (DO), simulation quantit

35、y input </p><p>　　The switch quantity is refers has and closes (or 1 and 0) two kind of conditions signals, the simulation quantity is only a quantity which refers continuously changes. Commonly used I/O cla

36、ssifies as follows:</p><p>　　Switch quantity: Divides equally according to the voltage water, has 220VAC, 110VAC, 24VDC, divides according to the isolation way, has the relay isolation and the transistor iso

37、lation. </p><p>　　Simulation quantity: Divides according to the signal type, has the electric current (4-20mA,0-20mA), the voltage (0-10V,0-5V, -10-10V) and so on, divides according to the precision, has 12b

38、it,14bit,16bit and so on. </p><p>　　Besides above general I/O, but also has the special I/O module, like module and so on thermal resistance, thermo-element, pulse. </p><p>　　According to the I/

39、O points determination module specification and the quantity, the I/O module may be many may be few, but its biggest number the basic disposition ability which can manage CPU, namely biggest ledger wall or rack Key slot

40、number limit.</p><p>　　Fifth, power source module</p><p>　　The PLC power source uses in is the PLC various modules integrated circuit provides the work power source. At the same time, some also

41、provides 24V for the input circuit the work power source. The mains input type includes: (What the alternating current supply (220VAC or 110VAC), the direct-current power supply is commonly used is 24VAC).</p><

42、;p>　　Sixth, ledger wall or rack</p><p>　　The majority module type PLC use ledger wall or the rack, its function is: On the electricity, realizes during various modules relation, enables CPU to visit on th

43、e ledger wall all modules, on the machinery, realizes during various modules connection, enable various modules to constitute a whole.</p><p>　　Seventh, PLC system other equipment</p><p>　　1st,

44、programs the equipment: The programming is the PLC development application, the monitor movement, the inspection maintains the essential component, uses in to program, makes some hypotheses to the system, monitors the sy

45、stem working condition which PLC and PLC controls, but it not directly participates in the scene control movement. Small programming PLC generally has the grasping programming, at present generally (movement programming

46、software) acts as the programming by the computer. </p><p>　　2nd, man-machine contact surface: The simplest man-machine contact surface is the indicating lamp and the button, at present the liquid crystal sc

47、reen (or touches screen) a formula writing style operator terminal application to be more and more widespread, (movement configuration software) acts as the man-machine contact surface by the computer extremely to popula

48、rize. </p><p>　　3rd, input-output device: Uses in permanently the memory user data, like EPROM, EEPROM reading in, bar code microreader, input simulation quantity potentiometer, printer and so on.</p>

49、<p>　　Eighth, PLC correspondence networking</p><p>　　Depends upon the advanced industry network technology to be allowed rapidly effectively to collect, the transmission produces and manages the data.

50、Therefore, the network is more and more remarkable in the automated system integration project importance, even some people proposed the "network is the controller" viewpoint view. </p><p>　　PLC ha

51、s the correspondence networking the function, it causes between PLC and PLC, PLC and on between the position computer and all that intelligent equipment can exchange the information, forms a unified whole, the realizatio

52、n disperser common control. Most PLC has the RS-232 connection, but also has some in sets has supports respective correspondence agreement the connection.</p><p>　　PLC correspondence, but also the realizatio

53、n mutually has not been operational, IEC had stipulated the many kinds of field bus standard, the PLC various factories have the use. </p><p>　　(Specially is center large-scale control system) says regarding

54、 an automated project, the choice network count for much. First, the network will have to be open, facilitates the different equipment the integration and the future system scale expansion; Next, in view of the different

55、 network level transmission performance requirement, the choice network form, this must in thoroughly understand this network standard the agreement, under the mechanism premise carries on; Once more, the synthesis co<

56、;/p><p>　　Today, the big unit growth in the PLC industy is at the low end-where small keeps getting smaller. When a few years ago the micro PLC entered the market, some thougt that these devices had “bottomed o

57、ut”. Now,nano PLCs-generally defined as those with 16 or fewer I/O-are spreading. Some can fit into your shirt pocket, being no larger than a deck of cards and at the time of this writing, PLC Direct plants to introduce

58、a PLC the size of a box of Tic-Tac candy that will include many features of curr</p><p>　　The first PLC systems evolved from conventional computers in the late 1960s and early 1970s. These first PLCs were in

59、stalled primarily in automotive plants. Traditionally, The auto plants had to be shut down for up to a month at model changeover time. The early PLCs were used along with other new automation techniques to shorten the c

60、hangeover time. One of the major time-consuming changeover procedures had been the wiring of new or revised relay and control panels. The PLC keyboard reprogrammin</p><p>　　There was a major problem with the

61、se early 1970s computer/PLC reprogramming procedures. The programs were complicated and required a highly trained programmer to make the changes. Through the late 1970s, improvements were made in PLC programs to make the

62、m somewhat more user friendly; in 1978, the introduction of the microprocessor chip increased computer power for all kinds of automotion systems and lowered the computing cost. Robotics, automotion devices, and computers

63、 of all types, including t</p><p>　　In the 1980s, with more computer power per dollar available, the PLC came into exponentially increasing use. Some large electronics and computer companies and some diverse

64、 corporate electronics divisions found that the PLC had become their greatest volume product. The market for PLCs grew from a volume of $80 million in 1978 to $1 billion per year by 1990 and is still growing. Even the ma

65、chine tool industry, where compute numerical controls (CNCs) have been used in the past, is using PLCs. PLCs </p><p>　　A person knowledgeable in relay logic systems can master the major PLC functions in a fe

66、w hours, These functions might include coils, contacts, timers and counters. The same is true for a person with a digital logic background. For persons unfamiliar with ladder diagrams or digital principles, howere, the l

67、earning process takes more time.</p><p>　　A person knowledgeable in relay logic can master advanced PLC functions in a few days with proper instruction. Company schools and operating manuals are very helpful

68、 in mastering these advanced functions. Advanced functions in order of learning might include sequence/drum controller, register bit use, and more functions.</p><p>　　Following are 8 major advantages of usin

69、g a programmable controller.</p><p>　?、貴lexibility. In the past, each different electronically controlled production machine required own controller; 15 machines might require 15 different controllers. Now i

70、t is possible to use just one model of a PLC to run any one of the 15 machines. </p><p>　?、贗mplementing Change and Correcting Errors. With a wired relay-type panel, any program alterations require time for r

71、ewriting of panels and devices. When a PLC program circuit or sequence design change is made, the PLC program can be changed from a keyboard sequence in a metter of minutes. No rewiring is required for a PLC-controlled s

72、ystem.</p><p>　?、跮arge quantities of contacts. The PLC has a large number of contacts for each coil available in its programming.suppose that a panel-wired relay has four contacts and all are in use when a d

73、esign change requiring three more contacts is made. Time would have to be taken to procure and install a new relay or relay contact block. Using a PLC, howere, only three more contacts would be typed in. the three contac

74、t would be automatically available in the PLC. Indeed, a hundred contacts can be used fro</p><p>　?、躄ower cost. Increased technology makes it possible to condense more functions into smaller and less expensi

75、ve packages. Now you can purchase a PLC with numerous relays, timers and counters, a sequencer, and other function for a few hundred dollars.</p><p>　?、軵ilot Running. A PLC programmed circuit can be evaluate

76、d in the office or lab. The program can be typed in, tested, observed, and modified if needed, saving valuable factory time. In contrast, conventional relay systems have been tested on the factory floor, which can be ver

77、y time consuming.</p><p>　?、轛isual Observation. A PLC circuit’s operation can be seen during operation directly on a CRT screen. The operation or misoperation of a circuit can be observed as it happens. Logi

78、c paths light up on the screen as they are energized. Troubleshooting can be done more quickly during visual observation. In advanced PLC systems, an operator message can be programmed for each possible malfunction.</

79、p><p>　　In advanced PLC systems, an operator message can be programmed for each possible malfunction. The malfunction description appears on the screen when the malfunction is detected by the PLC logic. Advance

80、d PLC systems also may have descriptions of the function of each circuit component. </p><p>　?、逽peed of Operation. Relays can take an unacceptable amount of time to actuate. The operational speed for the PLC

81、 program is very fast. The speed for the PLC logic operation is determined by scan time, which is a matter of milliseconds.</p><p>　?、郘adder or Boolean Programming Method. The PLC programming can be accompli

82、shed in the ladder mode by an electrician or technician. Alternatively, a PLC programmer who works in digital or Boolean control systems can also easily perform PLC programming.</p><p>　　In modern industrial

83、 production equipment, and large numbers of simulations of the control devices, such as the cease electrical, electromagnetic devices to turn, the number of products, temperature, Ap power, and set the flow control, the

84、automatic control of the industrial site, If a programmable controller (PLC) to resolve the issue has become a cybernetic one of the most effective tools, this article describes Plc control system design should be noted.

85、 Hardware purchase many products current</p><p>　　First, the system should first determine the size of single control system with Plc or using Plc networking, thus calculating Plc importing, exporting. Few,

86、and in some Plc to be in real need have a certain cushion</p><p>　　Second, determine the type of load under Plc export-led type of load is the DC or exchange-type, big or small currents, and Plc export point

87、s such as the frequency of movements, the use of relays to determine export-export, or transistor output, or goods of export gates. Different load choose different ways to export to the operating system's stability i

88、s very important.</p><p>　　Third, the storage capacity and speed while foreign manufacturers of Plc products essentially the same, but there are some differences. Currently the company has not yet found full

89、 compatibility between products. The development of software companies are not the same, and users of storage capacity and procedures to implement the Directive speed are two important indicators. General greater storage

90、 capacity, faster speed on the Plc higher prices, but should be based on system size reasonable choi</p><p>　　Fourth, programming devices Plc programming can purchase three ways : Using hand-held programmi

91、ng device programming in general, it can provide businesses phrases programming language table. This approach inefficient, but the capacity of small systems, the products more suitable for small consumption, and small si

92、ze, ease of debugging scene, but also lower costs. Using graphical programming device programming, the programming device used Trapezoid Chart programming for visual and general elect</p><p>　　Fifth, And lar

93、ge companies to choose their quality guaranteed products, and good technical support, after sales services are generally better, but also help expand your product and software upgrades.</p><p>　　For small sy

94、stems, such as 80 points within the system. Generally do not need expansion; When a larger system, we must expand. Different companies products to the total points system and the expansion of the number of modules have l

95、imitations when expansion can not meet the requirements, can network structure; At the same time, some manufacturers of individual products do not support the expansion module directives, in software development, we must

96、 pay attention to. When using such simulation mo</p><p>　　When using a Plc network design, its much more difficult to control than single Plc. First you should choose their own more familiar type, its basic

97、instructions and a more in-depth understanding of the functional commands, and the speed and direction of the implementation of storage capacity users should also be careful about the procedure. Otherwise, you can not ad