外文翻譯-可編程控制器技術(shù)討論與未來發(fā)展

1、<p><b>　　附錄</b></p><p><b>　　外文資料</b></p><p>　　PLC technique discussion and future development</p><p>　　Along with the development of the ages, the techn

2、ique that is nowadays is also gradually perfect, the competition plays more strong; the operation that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also

3、can't guarantee the request of the higher quantity and high new the image of the technique business enterprise.</p><p>　　The people see in produce practice, automate brought the tremendous convenience an

4、d the product quantities for people up of assurance, also eased the personnel's labor strength, reduce the establishment on the personnel. The target control of the hard realization in many complicated production lin

5、es, whole and excellent turn, the best decision etc., well-trained operation work, technical personnel or expert, governor but can judge and operate easily, can acquire the satisfied result. The researc</p><p&

6、gt;　　We come in sight of the control that links after the electric appliances in various situation, that is already the that time generation past, now of after use in the mold a perhaps simple equipments of grass-roots c

7、ontrol that the electric appliances can do for the low level only; And the PLC emergence also became the epoch-making topic, adding the vivid software control through a very and stable hardware, making the automation hea

8、d for the new high tide.</p><p>　　The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importa

9、tion that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the

10、 electric appliances, but the exportation equipments direct conjunction of the small power can.</p><p>　　PLC internal containment have the CPU of the CPU, and take to have an I/ O for expand of exterior to c

11、onnect a people's address and saving machine three big pieces to constitute, CPU core is from an or many is tired to add the machine to constitute, mathematics that they have the logic operation ability, and can read

12、 the procedure save the contents of the machine to drive the homologous saving machine and I/ Os to connect after pass the calculation; The I/ O add inner part is tired the input and</p><p>　　The PLC anti- i

13、nterference is very and excellent, our root need not concern its service life and the work 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 i

14、nternal resources of make use of the PLC to strengthen the control ability of the equipments for us, make our equipments more gentle.</p><p>　　PLC language is not we imagine of edit collected materials the l

15、anguage or language of Cs to carry on weaving the distance, but the trapezoid diagram that the adoption is original after the electric appliances to control, make the electrical engineering teacher while weaving to write

16、 the procedure very easy comprehended the PLC language, and a lot of non- electricity professional also very quickly know and go deep into to the PLC.</p><p>　　Is PLC one of the advantage above and only, thi

17、s is also one part that the people comprehend more and easily, in a lot of equipments, the people have already no longer hoped to see too many control buttons, they damage not only and easily and produce the artificial e

18、rror easiest, small is not a main error perhaps you can still accept; But lead even is a fatal error greatly is what we can't is tolerant of. New technique always for bringing more safe and convenient operation for u

19、s, make we a lot </p><p>　　HMI the control not only is reduced the control press 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

20、feedback with data, control in the temperature curve of imitate but also can keep the manifestation of view to come out. And can write the function help procedure through a plait to provide the help of various what lies

21、in one's power, the one who make operate reduces the otiose error. Currently the HMI factory is also</p><p>　　At a lot of situations, the list is a smooth movement that can't guarantee the equipments

22、 by the control of the single machine, but pass the information exchanges of the equipments and equipments to attain the result that we want. For example fore pack and the examination of the empress work preface, we will

23、 arrive wrapping information feedback to examine the place, and examine the information of the place to also want the feedback to packing. Pass the information share thus to make both the cha</p><p>　　The PL

24、C correspondence has already come more body now its value, at the PLC and correspondence between PLCs, can pass the communication of the information and the share of the dates to guarantee that of the equipments moderate

25、s mutually, the result that arrive already to repair with each other. Data conversion the adoption RS232 between PLC connect to come to the transmission data, but the RS232 pick up a people and can guarantee 10 meters on

26、ly of deliver the distance, if in the distance of 1000</p><p>　　The PLC data 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 o

27、ther party, we, the PLC of the other party passes to read data in the watch to carry on the operation. If the data that data in the watch is a to establish generally, that is just the general data transmission, for examp

28、le today of oil price rise, I want to deliver the price of the oil price to lose the oil ally on board, that is the share of the data; Bu</p><p>　　The form that information transport contain single work, the

29、 half a work and the difference of a workers .The meaning of the single work also is to say 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 ca

30、n't give the superior reply; A work of half is also 2 and can send out similar to accept 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

31、 phone, the </p><p>　　The process that information transport also has synchronous and different step cent: The data line and the clock lines are synchronous when synchronous meaning lie in sending out the da

32、ta, is also the data signal and the clock signals to be carry on by the CPU to send out at the same time, this needs to all want the specialized clock signal each other to carry on the transmission and connect to send, a

33、nd is constrained, the characteristics of this kind of method lies in its speed very quick, but</p><p>　　And the different step is an application the most extensive, this receive benefit in it of technique d

34、ifficulty is opposite and want to be small, at the same time not need to prepare the specialized clock signal, its characteristics to lie in, its data is partition, the long-lost send out and accept, be the CPU is too bu

35、sy of time can grind to a stop sex to work, also reduced the difficulty on the hardware, the data throw to lose at the same time opposite want to be little, we can pass the exami</p><p>　　A line of transmiss

36、ion of the information contains a string of and combine the cent of: The usual PLC is 8 machines, 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 ca

37、n be 88 send out the data to the other party, an and 8 differentiations are also the as that 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 sol

38、ve problem, and can use the telephone lin</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 of circumstance no

39、t 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 correspondence, b

40、ecause 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 knock on door, you st

41、op 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 telephone through,

42、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 authorit</p>

43、;<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 Class according to pe

44、rson'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 internal PLC, also follow

45、ing 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 the interruption and

46、 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't comprehend t

47、he 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 we meet the urgen

48、t 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 for processing the

49、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</p><p&g

50、t;　　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 they also can keep

51、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 class counts the mac

52、hine, 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, calculating high

53、-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 counts the machine</

54、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't result in pro

55、cedure 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 jump to turn the mi

56、stake 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 mode of the one, and

57、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 control, and cans p

58、ass 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 development of the

59、 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 generation, coming to the c

60、ontinuous 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 control system desig

61、n.</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 of industrial auto

62、mation 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 when they would be be

63、st 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 stands for "Americ

64、an 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 equipment. The receiving e

65、quipment 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 intelligent PLC mo

66、dule 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, as shown in Fig. 2

67、A, 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 they are dissipate

68、d by terminators at each end of the bus.</p><p>　　CPU: This stands for "central processing unit," which actually is that part of a computer, PLC, or other intelligent device where arithmetic and lo

69、gical operations are performed and instructions are decoded and executed.</p><p>　　Daisy chain: This is a description of the connection of individual devices in a PLC network, where, as shown in Fig. 3, each

70、 device is connected to the next and communications signals pass from one unit to the next in a sequential fashion.</p><p>　　Distributed control: This is an automation concept in which portions of an automat

71、ed system are controlled by separate controllers, which are located in close proximity to their area of direct control (control is decentralized and spread out over the system).</p><p>　　Host computer: This

72、is a computer that's used to transfer data to, or receive data from, a PLC in a PLC/computer network.</p><p>　　Intelligent device: This term describes any device equipped with its own CPU.</p><

73、;p>　　I/O: This stands for "inputs and outputs," which are modules that handle data to the PLC (inputs) or signals from the PLC (outputs) to an external device.</p><p>　　Kbps: This stands for &qu

74、ot;thousand bits per second," which is a rate of measure for electronic data transfer.</p><p>　　Mbps: This stands for "million bits per second."</p><p>　　Node: This term is applie

75、d to any one of the positions or stations in a network. Each node incorporates a device that can communicate with all other devices on the network.</p><p>　　Protocol: The definition of how data is arranged a

76、nd coded for transmission on a network.</p><p>　　Ring topology. This is a LAN arrangement, as shown in Fig. 2C, in which each node is connected to two other nodes, resulting in a continuous, closed, circular

77、 path or loop for messages to circulate, usually in one direction. Some ring topologies have a special "loop back" feature that allows them to continue functioning even if the main cable is severed.</p>

78、<p>　　RS232. This is an IEEE standard for serial communications that describes specific wiring connections, voltage levels, and other operating parameters for electronic data communications. There also are several o

79、ther RS standards defined.</p><p>　　Serial: This is an electronic data transfer scheme in which information is transmitted one bit at a time.</p><p>　　Serial port: This the communications access

80、 point on a device that is set up for serial communications.</p><p>　　Star topology. This is a LAN arrangement in which, as shown in Fig. 2B, nodes are connected to one another through a central hub, which c

81、an be active or passive. An active hub performs network duties such as message routing and maintenance. A passive central hub simply passes the message along to all the nodes connected to it.</p><p>　　Topolo

82、gy: This relates to a specific arrangement of nodes in a LAN in relation to one another.</p><p>　　Transparent: This term describes automatic events or processes built into a system that require no special pr

83、ogramming or prompting from an operator.</p><p>　　Now that we're familiar with these terms, let's see how they are used in describing the available PLC network options.</p><p>　　PLC netw

84、ork options</p><p>　　PLC networks provide you with a variety of networking options to meet specific control and communications requirements. Typical options include remote I/O, peer-to-peer, and host compute

85、r communications, as well as LANs. These networks can provide reliable and cost-effective communications between as few as two or as many as several hundred PLCs, computers, and other intelligent devices.</p><

86、p>　　Many PLC vendors offer proprietary networking systems that are unique and will not communicate with another make of PLC. This is because of the different communications protocols, command sequences, error-checking

87、 schemes, and communications media used by each manufacturer.</p><p>　　However, it is possible to make different PLCs "talk" to one another; what's required is an ASCII interface for the connec

88、tion(s), along with considerable work with software.</p><p>　　Remote I/0 systems</p><p>　　A remote I/O configuration, as shown in Fig. 4A, has the actual inputs and outputs at some distance from

89、 the controller and CPU. This type of system, which can be described as a "master-and-slave" configuration, allows many distant digital and analog points to be controlled by a single PLC. Typically, remote I/Os

90、 are connected to the CPU via twisted pair or fiber optic cables.</p><p>　　Remote I/O configurations can be extremely cost-effective control solutions where only a few I/O points are needed in widely separat

91、ed areas. In this situation, it's not always necessary, or practical for that matter, 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 CP

92、U. For example, remote I/O systems can be used in acquiring data from remote plant or facility locations. Information such as cycle times, counts, durat</p><p>　　In a remote I/O configuration, the master con

93、troller polls the slaved I/O for its current I/O status. The remote I/O system responds, and 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 m

94、emory. This entire cycle occurs hundreds of times per second.</p><p>　　Peer-to-peer networks</p><p>　　Peer-to-peer networks, as shown in Fig. 4B, enhance reliability by decentralizing the contro

95、l functions without sacrificing coordinated control. In this type of network, numerous PLCs are connected to one another in a daisy-chain fashion, and a common memory table is duplicated in the memory of each. In this wa

96、y, when any PLC writes data to this memory area, the information is automatically transferred to all other PLCs in the network. They then can use this information in their own operating pr</p><p>　　With peer

97、-to-peer networks, each PLC in the network is responsible for its own control site and only needs to be programmed for its own area of responsibility. This aspect of the network significantly reduces programming and debu

98、gging complexity; because all communications occur transparently to the user, communications programming is reduced to simple read-and-write statements.</p><p>　　In a peer-to-peer system, there's no mast

99、er PLC. However, it's possible to designate one of the PLCs as a master for use as a type of group controller. This PLC then can be used to accept input information from an operator input terminal, for example, sendi