plc畢業(yè)設(shè)計文獻翻譯--plc的發(fā)展

1、<p>　　PLC development</p><p>　　1、PLC overview </p><p>　　Programmable controller is the first in the late 1960s in the United States, then called Plc programmable logic controller (Programm

2、able Logic Controller) is used to replace relays. For the implementation of the logical judgment, timing, sequence number, and other control functions. The concept is presented Plc General Motors Corporation. Plc and the

3、 basic design is the computer functional improvements, flexible, generic and other advantages and relay control system simple and easy to operate, s</p><p>　　In the mid-1970s, the Plc has been widely used as

4、 a central processing unit microprocessor, import export module and the external circuits are used, large-scale integrated circuits even when the Plc is no longer the only logical (IC) judgment functions also have data p

5、rocessing, PID conditioning and data communications functions. International Electro technical Commission (IEC) standards promulgated programmable controller for programmable controller draft made the following definitio

6、n: programm</p><p>　　First, high reliability, anti-interference capability; </p><p>　　Second，programming visual, simple; </p><p>　　Third, adaptability good; </p><p>　　F

7、ourth, functional improvements, strong functional interface. </p><p>　　2、History of PLC </p><p>　　Programmable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968,

8、have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-call

9、ed relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days [Moody and Morley, </p><p>　　Although PC b

10、ased control has started to come into place, PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability i

11、n harsh environments. Moreover, according to a study on the PLC market of Frost and Sullivan [1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US do

12、llars has been predicted, though the prices of </p><p>　　Though PLCs are widely used in industrial practice, the programming of PLC based control systems is still very much relying on trial-and-error. Alike

13、software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating. </p><p>　　If houses were built like

14、software projects, a single woodpecker could destroy civilization.” </p><p>　　Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old lad

15、der logic programs. Though the hardware costs of PLCs are dropping continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used. </p><p>　　In gener

16、al, the productivity in generating PLC is far behind compared to other domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not

17、necessarily applicable to the PLC based software design because PLC-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. I

18、n many industrial design projects, more than of the </p><p>　　In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and recon figurability of

19、manufacturing systems. A further problem, impelling the need for a systematic design methodology, is the increasing software complexity in large-scale projects. </p><p>　　The objective of this thesis is to d

20、evelop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discre

21、te event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in

22、 managing the control so</p><p>　　3、now of PLC </p><p>　　From the structure is divided into fixed PLC and Module PLC, the two kinds of PLC including CPU board, I/O board, display panel, memory b

23、lock, power, these elements into a do not remove overall. Module type PLC including CPU module, I/O modules, memory, the power modules, bottom or a frame, these modules can be according to certain rules combination confi

24、guration. </p><p>　　In the user view, a detailed analysis of the CPU's internal unnecessary, but working mechanism of every part of the circuit. The CPU control works, by it reads CPU instruction, interp

25、rets the instruction and executes instructions. But the pace of work by shock signal control. </p><p>　　Unit work under the controller command used in a digital or logic operations. In computing and storage

26、 register of computation result, it is also among the controller command and work. CPU speed and memory capacity is the important parameters of PLC. Its determines the PLC speed of work, IO PLC number and software capaci

27、ty, so limits to control size. </p><p>　　Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such a

28、s 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola

29、microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PL</p><p>　　System memory (today mostly implemented in FLASH technology) is used by a PLC for

30、a process control system. Aside form. this operating system it also contains a user program translated forma ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being

31、changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use o</p><p>　

32、　User memory is divided into blocks having special functions. Some parts of a memory are used for storing input and output status. The real status of an input is stored either as “1”or as “0”in a specific memory bit/ eac

33、h input or output has one corresponding bit in memory. Other parts of memory are used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part

34、of the memory.</p><p>　　PLC controller can be reprogrammed through a computer (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed throu

35、gh a computer if you have the software needed for programming. Today’s transmission computers are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is co

36、rrected, it is also important to read the right program into a PLC again. It is also good to chec</p><p>　　Almost every program for programming a PLC controller possesses various useful options such as: forc

37、ed switching on and off of the system input/outputs (I/O lines), program follow up in real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programm

38、er can add remarks, names of input or output devices, and comments that can be useful when finding errors, or with system maintenance. Adding comments and remarks enables any techn</p><p>　　Electrical supply

39、 is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220 VAC. On some PLC controllers you’ll find electrical supply as a separate module. Those are usually bigg

40、er PLC controllers, while small and medium series already contain the supply module. User has to determine how much current to take from I/O module to ensure that electrical supply provides appropriate amount of current.

41、 Different types of modules use different a</p><p>　　This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs beca

42、use then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs w

43、ith voltage from a small supply source already incorporated into a PLC. </p><p>　　4、PLC design criteria </p><p>　　A systematic approach to designing PLC software can overcome deficiencies in th

44、e traditional way of programming manufacturing control systems, and can have wide ramifications in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state ma

45、chines. Formal representations provide a high-level description of the behavior of the system to be controlled. State machines can be analytically evaluated as to whether or not they meet the desired g</p><p&g

46、t;　　In modern manufacturing, systems are characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements. A major challenge is therefore to provide

47、 enabling technologies that can economically reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a si

48、gnificant competitive edge in industrial practice. </p><p>　　Studies have shown that programming methodologies in automation systems have not been able to match rapid increase in use of computing resources.

49、For instance, the programming of PLCs still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a major stumbling stone for the progress of manu

50、facturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60</p><p>　　A systematic approach will increase the level of design automat

51、ion through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliability and will be relevant to systems high sec

52、urity standards, especially those having hazardous impact on the environment such as airport control, and public railroads. </p><p>　　The software industry is regarded as a performance destructor and complex

53、ity generator. Steadily shrinking hardware prices spoils the need for software performance in terms of code optimization and efficiency. The result is that massive and less efficient software code on one hand outpaces th

54、e gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software redesign and maintenance-essential in modern automation systems-becomes</p>&

55、lt;p>　　Today, the primary focus of most design research is based on mechanical or electrical products. One of the by-products of this proposed research is to enhance our fundamental understanding of design theory and

56、methodology by extending it to the field of engineering systems design. A system design theory for large-scale and complex system is not yet fully developed. Particularly, the question of how to simplify a complicated or

57、 complex design task has not been tackled in a scientific way. Further</p><p>　　From a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs a

58、re extremely complex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a component design and a system design stage. At component design s

59、tage, single functions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is te</p><p>　　5、AK 1703 ACP </p><p>　　Followi

60、ng the principle of our product development, AK 1703 ACP has high functionality and flexibility, through the implementation of innovative and reliable technologies, on the stable basis of a reliable product platform. <

61、;/p><p>　　For this, the system concept ACP (Automation, Control and Protection) creates the technological preconditions. Balanced functionality permits the flexible combination of automation, telecontrol and co

62、mmunication tasks. Complemented with the scalable performance and various redundancy configurations, an optimal adaptation to the respective requirements of the process is achieved. </p><p>　　AK 1703 ACP is

63、thus perfectly suitable for automation with integrated telecontrol technology as: </p><p>　　* Telecontrol substation or central device </p><p>　　* Automation unit with autonomous functional grou

64、ps </p><p>　　* Data node, station control device, front-end or gateway </p><p>　　* With local or remote peripherals </p><p>　　* For rear panel installation or 19 inch assembly </

65、p><p>　　* Branch-neutral product, therefore versatile fields of application and high product stability </p><p>　　* Versatile communication </p><p>　　* Easy engineering </p><

66、p>　　* Plug & play for spare parts </p><p>　　* Open system architecture </p><p>　　* Scalable redundancy </p><p>　　* The intelligent terminal - TM 1703 </p><p>　　T

67、he Base Unit AK 1703 ACP with Peripheral Elements has one basic system element CP-2010/CPC25 (Master control element) and CP-2012/PCCE25 (Processing and communication element) ,one bus line with max. 16 peripheral elemen

68、ts can be connected. </p><p>　　CP-2010/CPC25 Features and Functions </p><p>　　System Functions: </p><p>　　* Central element, coordinating all system services </p><p>　　

69、Central hub function for all connected basic system elements </p><p>　　* Time management </p><p>　　Central clock of the automation unit </p><p>　　Setting and keeping the own clock’s

70、 time with a resolution of 10ms </p><p>　　Synchronization via sired communication via LAN or local </p><p>　　* Redundancy </p><p>　　Voting and change-over for redundant processing a

71、nd communication elements of the own automation unit</p><p>　　Supports voting and change-over by an external SCA-RS redundancy </p><p><b>　　Switch</b></p><p>　　Supports

72、application voting and change-over by an external system, e.g.a control system </p><p>　　* SAT TOLLBOX|| connection </p><p>　　Storing firmware and parameters on a Flash Card </p><p>

73、;　　Communication: </p><p>　　* Communication via installable protocol elements to any superior or </p><p>　　subordinate automation unit </p><p>　　* Automatic data flow routing </p

74、><p>　　* Priority based data transmission (priority control) </p><p>　　* Own circular buffer and process image for each connected station (data keeping) </p><p>　　* Redundant communica

75、tion routes </p><p>　　Communication with redundant remote stations </p><p>　　* Special application specific functions for dial-up traffic </p><p>　　Test if stations are reachable &l

76、t;/p><p>　　Process Peripherals: </p><p>　　* Transmission of spontaneous information objects from and to peripheral elements, via the serial Ax 1703 peripheral bus </p><p>　　Functions f

77、or Automation: </p><p>　　* Open-/closed-loop control function for the execution of freely definable user programs which are created with CAEX plus according to IEC 61131-3,e.g.using function diagram technolo

78、gy </p><p>　　512KB for user program </p><p>　　Approx 50.000 variables and signals, 2.000 of them retained </p><p>　　Cycle of 10ms or a multiphase thereof </p><p>　　Onl

79、ine test </p><p>　　Loadable without service interruption </p><p>　　* Redundant open-/closed-loop control functions </p><p>　　Synchronization via redundancy link </p><p>

80、;　　Transmission of periodic process information between the </p><p>　　Open-/closed-loop control function and the peripheral elements, via the serial Ax 1703 peripheral bus </p><p>　　6、SIEMENS PL

81、C </p><p>　　SIMATIC S7-300 series PLC applied to all walks of life and various occasions in the detection, monitoring and control of automation, its power to both the independent operation of, or connected

82、to a network able to achieve complex control. </p><p>　　The photoelectric products with isolation, high electromagnetic compatibility; have high industrial applicability, allowing the ambient temperature of

83、 60 ℃; has strong anti-jamming and anti-vibration and impact resistance, so in a harsh working environment has been widely Applications. </p><p>　　I also mean freedom of communication S7-300 type PLC' s

84、 a very unique feature, which allows S7-300-PLC can deal openly with any other communications equipment, communications controller, or PLC S7-300 type can be defined by the user's own Communications protocol (of the

85、agreement ASCII), the baud rate to 1.5 M bit / s (adjustable). So that can greatly increase the scope of communications so that the control system configuration more flexible and convenient. Of any kind with a serial int

86、erface pe</p><p>　　When the PC offline, under the control of the next crew, the whole system can operate normally. </p><p>　　PC that is by control centre, mainly by the PC and laser printer com

87、ponents, using SIMATIC WINCC software platform, the all-Chinese interface, friendly man-machine dialogue. Managers and operators can be observed through a PC, shown in the various kinds of information to understand the p

88、resent and past the ice-storage operation of the automatic control system and all the parameters, and through the mouse to print equipment management and implementation tasks. </p><p>　　WINCC software in th

89、e field of automation can be used for all the operators’ control and monitoring tasks. Can be controlled in the process of the events clearly show, and shows the current status and order records, the recorded data can sh

90、ow all or select summary form, or may be required for editing, printing and output statements and trends . </p><p>　　WINCC able to control the critical situation in the early stages of the report, and the s

91、ignal can be displayed on the screen, can also use sound to be felt. It supported by online help and operational guidelines to eliminate failure. WINCC a workstation can be devoted to the process control to the process s

92、o that important information not is shielded. Software-assisted operation strategy ensures that the process was not illegal to visit and to provide for non-industrial environment in the wrong</p><p>　　WINCC

93、is MICRSOFT WINDOWS98 or WINDOWS NT4.0 operating system, running on a PC object-oriented class 32-bit application, OLE through the window and ODBC standard mechanism, as an ideal partner to enter the communications world

94、 WINDOWS, it can be easily WINCC To integrate a company-wide data processing system. </p><p>　　7、Communications </p><p>　　Communications are vital to an individual automation cell and to the au

95、tomated 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 band wagon. Many, however were disappointed when a fully-defined and completed MAP specificatio

96、n didn’t appear immediately. Says Larry Kumara:” Right now, MAP is still a moving target for the manufacturers specification that is not final. Presently, for example, people are introducing products to meet the </p&

97、gt;<p>　　Because of this, many PLC vendors are holding off on full MAP implementations. Omron, for example, has an ongoing MAP-compatibility program, but Frank Newborn, vice president of Omron’s Industrial Divisio

98、n, reports that because of the lack of a firm definition, Omron's PLCs don't yet talk to MAP. </p><p>　　Since it’s unlikely that an individual PLC would talk to broadband MAP anyway, makers are conce

99、ntrating n proprietary networks. According to Sal Provanzano, users fear that if they do get on board and vendors withdraw from MAP, they all pulse width modulation control system be the ones left holding a communication