plc方向畢業(yè)設計中英文翻譯---可編程控制器技術(shù)討論與未來發(fā)展

1、<p>　　PLC technique discussion and future development</p><p>　　Along with the development of the ages, the technique that is nowadays is also gradually perfect, the competition plays more strong; the op

2、eration that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also can't guarantee the request of the higher quantity and high new the image of the techn

3、ique business enterprise.</p><p>　　The people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel's labor

4、strength, reduce the establishment on the personnel. The target control of the hard realization in many complicated production lines, whole and excellent turn, the best decision etc., well-trained operation work, technic

5、al personnel or expert, governor but can judge and operate easily, can acquire the satisfied result. The researc</p><p>　　We come in sight of the control that links after the electric appliances in various s

6、ituation, that is already the that time generation past, now of after use in the mold a perhaps simple equipments of grass-roots control that the electric appliances can do for the low level only; And the PLC emergence a

7、lso became the epoch-making topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide.</p><p>　　The PLC biggest characteristics lie in: The

8、 electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can

9、 solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipments direct conjunction of the small power

10、 can.</p><p>　　PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to connect a people's address and saving machine three big pieces to constitute, CPU core

11、is from an or many is tired to add the machine to constitute, mathematics that they have the logic operation ability, and can read the procedure save the contents of the machine to drive the homologous saving machine and

12、 I/ Os to connect after pass the calculation; The I/ O add inner part is tired the input and</p><p>　　The PLC anti- interference is very and excellent, our root need not concern its service life and the work

13、 situation bad, these all problems have already no longer become the topic that we fail, but stay to our is a concern to come to internal resources of make use of the PLC to strengthen the control ability of the equipmen

14、ts for us, make our equipments more gentle.</p><p>　　PLC language is not we imagine of edit collected materials the language or language of Cs to carry on weaving the distance, but the trapezoid diagram that

15、 the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write the procedure very easy comprehended the PLC language, and a lot of non- electricity prof

16、essional also very quickly know and go deep into to the PLC.</p><p>　　Is PLC one of the advantage above and only, this is also one part that the people comprehend more and easily, in a lot of equipments, the

17、 people have already no longer hoped to see too many control buttons, they damage not only and easily and produce the artificial error easiest, small is not a main error perhaps you can still accept; But lead even is a f

18、atal error greatly is what we can't is tolerant of. New technique always for bringing more safe and convenient operation for us, make we a lot </p><p>　　HMI the control not only is reduced the control pr

19、ess button, increase the vivid of the control, more main of it is can sequence of, and at can the change data input to output the feedback with data, control in the temperature curve of imitate but also can keep the mani

20、festation of view to come out. And can write the function help procedure through a plait to provide the help of various what lies in one's power, the one who make operate reduces the otiose error. Currently the HMI f

21、actory is also</p><p>　　At a lot of situations, the list is a smooth movement that can't guarantee the equipments by the control of the single machine, but pass the information exchanges of the equipment

22、s and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will arrive wrapping information feedback to examine the place, and examine the information of

23、 the place to also want the feedback to packing. Pass the information share thus to make both the cha</p><p>　　The PLC correspondence has already come more body now its value, at the PLC and correspondence b

24、etween PLCs, can pass the communication of the information and the share of the dates to guarantee that of the equipments moderates mutually, the result that arrive already to repair with each other. Data conversion the

25、adoption RS232 between PLC connect to come to the transmission data, but the RS232 pick up a people and can guarantee 10 meters only of deliver the distance, if in the distance of 1000</p><p>　　The PLC data

26、transmission is just to be called a form to it in a piece of and continuous address that the data of the inner part delivers the other party, we, the PLC of the other party passes to read data in the watch to carry on th

27、e operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for example today of oil price rise, I want to deliver the price of the oil price to lose the oil a

28、lly on board, that is the share of the data; Bu</p><p>　　The form that information transport contain single work, the half a work and the difference of a workers .The meaning of the single work also is to sa

29、y both, a can send out only, but a can receive only, for example a spy he can receive the designation of the superior only, but can't give the superior reply; A work of half is also 2 and can send out similar to acce

30、pt the data, but can't send out and accept at the same time, for example when you make a phone call is to can't answer the phone, the </p><p>　　The process that information transport also has synchro

31、nous and different step cent: The data line and the clock lines are synchronous when synchronous meaning lie in sending out the data, is also the data signal and the clock signals to be carry on by the CPU to send out at

32、 the same time, this needs to all want the specialized clock signal each other to carry on the transmission and connect to send, and is constrained, the characteristics of this kind of method lies in its speed very quick

33、, but</p><p>　　And the different step is an application the most extensive, this receive benefit in it of technique difficulty is opposite and want to be small, at the same time not need to prepare the speci

34、alized clock signal, its characteristics to lie in, its data is partition, the long-lost send out and accept, be the CPU is too busy of time can grind to a stop sex to work, also reduced the difficulty on the hardware, t

35、he data throw to lose at the same time opposite want to be little, we can pass the exami</p><p>　　A line of transmission of the information contains a string of and combine the cent of: The usual PLC is 8 ma

36、chines, certainly also having 16 machines. We can be an at the time of sending out the data a send out to the other party, also can be 88 send out the data to the other party, an and 8 differentiations are also the as th

37、at we say to send out the data and combine sends out the data. A speed is more and slowly, but as long as 2 or three lines can solve problem, and can use the telephone lin</p><p>　　Under a lot of circumstanc

38、es we are total to like to adopt the string to combine the conversion chip to carry on deliver, under this kind of circumstance not need us to carry on to deposited the machine to establish too and complicatedly, but car

39、ry 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

40、 of sending out the data, it can't</p><p>　　When you are reading the book, you hear someone knock on door, you stop to start up of affair, open the door and combine to continue with the one who knock on

41、door a dialogue, the telephone of this time rang, you signal hint to connect a telephone, after connecting the telephone through, return overdo come together knock on door to have a conversation, after dialogue complete,

42、 you continue again to see your book, this kind of circumstance we are called the interruption to it, it has the authorit</p><p>　　The interruption is not only a, sometimes existing jointly with the hour sev

43、eral inside break, break off to have the preferred Class, they will carry out the interruption of the higher Class according to person's request. This kind of breaks off the medium interruption to also became to brea

44、k off the set. The Class that certainly break off is relevant according to various resources of CPU with internal PLC, also following a heap of capacity size of also relevant fasten.</p><p>　　The contents th

45、at break off has a lot of kinds, for example the exterior break off, correspondence in of send out and accept the interruption and settle and the clock that count break off, still have the WDT to reset the interruption e

46、tc., they enriched the CPU to respond to the category while handle various business. Speak thus perhaps you can't comprehend the internal structure and operation orders of the interruption completely also, we do a ve

47、ry small example to explain.</p><p>　　Each equipment always will not forget a button, it also is at we meet the urgent circumstance use of, which is nasty to stop the button. When we meet the Human body trou

48、ble and surprised circumstances we as long as press it, the machine stops all operations immediately, and wait for processing the over surprised empress recover the operation again. Nasty stop the internal I/ O of the in

49、ternal CPU of the button conjunction PLC to connect up, be to press button an exterior to trigger signal for CP</p><p>　　When we are work a work piece, giving the PLC a signal, counting PLC inner part the ma

50、chine add 1 to compute us for a day of workload, a count the machine and can solve problem in brief, certainly they also can keep the data under the condition of dropping the electricity, urging the data not to throw to

51、lose, this is also what we hope earnestly.</p><p>　　The PLC still has the function that the high class counts the machine, being us while accept some dates of high speed, the high speed that here say is the

52、data of the in all aspects tiny second class, for example the bar code scanner is scanning the data continuously, calculating high-speed signal of the data processor DSP etc., we will adopt the high class to count the ma

53、chine to help we carry on count. It at the PLC carries out the procedure once discover that the high class counts the machine</p><p>　　You heard too many this phrases perhaps:" crash", the meaning

54、that is mostly is a workload of CPU to lead greatly, the internal resources shortage etc. the circumstance can't result in procedure circulate. The PLC also has the similar circumstance, there is a watchdog WDT in th

55、e inner part of PLC, we can establish time that a procedure of WDT circulate, being to appear the procedure to jump to turn the mistake in the procedure movement process or the procedure is busy, movement time of the pro

56、ce</p><p>　　The PLC development has already entered for network ages of correspondence from the mode of the one, and together other works control the net plank and I/ O card planks to carry on the share easi

57、ly. A state software can pass all se hardwires link, more animation picture of keep the view to carries on the control, and cans pass the Internet to carry on the control in the foreign land, the blast-off that is like t

58、he absolute being boat No.5 is to adopt this kind of way to make airship go up the sk</p><p>　　The development of the higher layer needs our continuous effort to obtain. The PLC emergence has already affecte

59、d a few persons fully, we also obtained more knowledge and precepts from the top one experience of the generation, coming to the continuous development PLC technique, push it toward higher wave tide.</p><p>

60、　　Knowing the available PLC network options and their best applications will ensure an efficient and flexible control system design.</p><p>　　The programmable logic controller's (PLC's) ability to su

61、pport a range of communication methods makes it an ideal control and data acquisition device for a wide variety of industrial automation and facility control applications. However, there is some confusion because so many

62、 possibilities exist. To help eliminate this confusion, let's list what communications are available and when they would be best applied.</p><p>　　To understand the PLC's communications versatility,

63、let's first define the terms used in describing the various systems.</p><p>　　ASCII: This stands for "American Standard Code for Information Interchange." As shown in Fig. 1, when the letter &q

64、uot;A" is transmitted, for instance, it's automatically coded as "65" by the sending equipment. The receiving equipment translates the "65" back to the letter "A." Thus, different d

65、evices can communicate with each other as long as both use ASCII code.</p><p>　　ASCII module: This intelligent PLC module is used for connecting PLCs to other devices also capable of communicating using ASCI

66、I code as a vehicle.</p><p>　　Bus topology: This is a linear local area network (LAN) arrangement, as shown in Fig. 2A, in which individual nodes are tapped into a main communications cable at a single point

67、 and broadcast messages. These messages travel in both directions on the bus from the point of connection until they are dissipated by terminators at each end of the bus.</p><p>　　CPU: This stands for "

68、central processing unit," which actually is that part of a computer, PLC, or other intelligent device where arithmetic and logical operations are performed and instructions are decoded and executed.</p><p

69、>　　Daisy chain: This is a description of the connection of individual devices in a PLC network, where, as shown in Fig. 3, each device is connected to the next and communications signals pass from one unit to the next

70、 in a sequential fashion.</p><p>　　Distributed control: This is an automation concept in which portions of an automated system are controlled by separate controllers, which are located in close proximity to

71、their area of direct control (control is decentralized and spread out over the system).</p><p>　　Host computer: This is a computer that's used to transfer data to, or receive data from, a PLC in a PLC/co

72、mputer network.</p><p>　　Intelligent device: This term describes any device equipped with its own CPU.</p><p>　　I/O: This stands for "inputs and outputs," which are modules that handle

73、 data to the PLC (inputs) or signals from the PLC (outputs) to an external device.</p><p>　　Kbps: This stands for "thousand bits per second," which is a rate of measure for electronic data transfer

74、.</p><p>　　Mbps: This stands for "million bits per second."</p><p>　　Node: This term is applied to any one of the positions or stations in a network. Each node incorporates a device th

75、at can communicate with all other devices on the network.</p><p>　　Protocol: The definition of how data is arranged and coded for transmission on a network.</p><p>　　Ring topology. This is a LAN

76、 arrangement, as shown in Fig. 2C, in which each node is connected to two other nodes, resulting in a continuous, closed, circular path or loop for messages to circulate, usually in one direction. Some ring topologies ha

77、ve a special "loop back" feature that allows them to continue functioning even if the main cable is severed.</p><p>　　RS232. This is an IEEE standard for serial communications that describes specif

78、ic wiring connections, voltage levels, and other operating parameters for electronic data communications. There also are several other RS standards defined.</p><p>　　Serial: This is an electronic data transf

79、er scheme in which information is transmitted one bit at a time.</p><p>　　Serial port: This the communications access point on a device that is set up for serial communications.</p><p>　　Star to

80、pology. This is a LAN arrangement in which, as shown in Fig. 2B, nodes are connected to one another through a central hub, which can be active or passive. An active hub performs network duties such as message routing and

81、 maintenance. A passive central hub simply passes the message along to all the nodes connected to it.</p><p>　　Topology: This relates to a specific arrangement of nodes in a LAN in relation to one another.&l

82、t;/p><p>　　Transparent: This term describes automatic events or processes built into a system that require no special programming or prompting from an operator.</p><p>　　Now that we're familiar

83、 with these terms, let's see how they are used in describing the available PLC network options.</p><p>　　PLC network options</p><p>　　PLC networks provide you with a variety of networking op

84、tions to meet specific control and communications requirements. Typical options include remote I/O, peer-to-peer, and host computer communications, as well as LANs. These networks can provide reliable and cost-effective

85、communications between as few as two or as many as several hundred PLCs, computers, and other intelligent devices.</p><p>　　Many PLC vendors offer proprietary networking systems that are unique and will not

86、communicate with another make of PLC. This is because of the different communications protocols, command sequences, error-checking schemes, and communications media used by each manufacturer.</p><p>　　Howeve

87、r, it is possible to make different PLCs "talk" to one another; what's required is an ASCII interface for the connection(s), along with considerable work with software.</p><p>　　Remote I/0 syst

88、ems</p><p>　　A remote I/O configuration, as shown in Fig. 4A, has the actual inputs and outputs at some distance from the controller and CPU. This type of system, which can be described as a "master-and

89、-slave" configuration, allows many distant digital and analog points to be controlled by a single PLC. Typically, remote I/Os are connected to the CPU via twisted pair or fiber optic cables.</p><p>　　Re

90、mote I/O configurations can be extremely cost-effective control solutions where only a few I/O points are needed in widely separated areas. In this situation, it's not always necessary, or practical for that matter,

91、to have a controller at each site. Nor is it practical to individually hard wire each I/O point over long distances back to the CPU. For example, remote I/O systems can be used in acquiring data from remote plant or faci

92、lity locations. Information such as cycle times, counts, durat</p><p>　　In a remote I/O configuration, the master controller polls the slaved I/O for its current I/O status. The remote I/O system responds, a

93、nd the master PLC then signals the remote I/O to change the state of outputs as dictated by the control program in the PLC's memory. This entire cycle occurs hundreds of times per second.</p><p>　　Peer-t

94、o-peer networks</p><p>　　Peer-to-peer networks, as shown in Fig. 4B, enhance reliability by decentralizing the control functions without sacrificing coordinated control. In this type of network, numerous PLC

95、s are connected to one another in a daisy-chain fashion, and a common memory table is duplicated in the memory of each. In this way, when any PLC writes data to this memory area, the information is automatically transfer

96、red to all other PLCs in the network. They then can use this information in their own operating pr</p><p>　　With peer-to-peer networks, each PLC in the network is responsible for its own control site and onl

97、y needs to be programmed for its own area of responsibility. This aspect of the network significantly reduces programming and debugging complexity; because all communications occur transparently to the user, communicatio

98、ns programming is reduced to simple read-and-write statements.</p><p>　　In a peer-to-peer system, there's no master PLC. However, it's possible to designate one of the PLCs as a master for use as a t

99、ype of group controller. This PLC then can be used to accept input information from an operator input terminal, for example, sending all the necessary parameters to other PLCs and coordinating the sequencing of various e