熱門關鍵詞： 自動灌裝封蓋機的PLC控制外文翻譯(全英語)
- 文件大小：116.22K
- 下載次數：
- 文件評級：
- 更新時間：2013-05-09
- 發 布 人：kuailexiaohuo
- 文件下載：
-
- 文件介紹：
- 該文件為 doc 格式，下載需要 20 積分
- 自動灌裝封蓋機的PLC控制外文翻譯The characteristics and trends of PLC, DCS and industrial PC
ABSTRACT: At present, widely used in industrial automation systems of the three large industrial PC, DCS and PLC. Here, for their economic and technological standards and development trends described.
KEYWORDS: PLC PC DCS automation trends
First, the characteristics and Application of PLC
1. PLC Application
Early PLC (Programmable Logic Controller, PLC), mainly to replace relay logic control to achieve. With computer technology, communications technology and the rapid development of automatic control technology, the PLC will be the traditional relay control technology and the emerging computer technology and communications technology integration, with high reliability, strong function and flexible, Programming simple, easy to use and a series of advantages, as well as good performance of the industrial environment and control targets of performance in industrial production in a wide range of applications.
1969, the United States Digital Equipment Corporation (DEC) developed the world's first programmable controller. Early separation from the programmable controller components and small and medium-sized integrated circuit component, the main function previously performed by the relay is completed sequence control, such as timing. The early 1970s, small size, strong function and cheaper microprocessors used PLC, makes the PLC function has been enhanced significantly. In terms of hardware, in addition to maintaining its original switch modules, has also increased the simulation module, remote I / O modules and special function modules all. In terms of software, easy to use PLC Electric staff in the ladder diagram programming language, in addition to maintaining the original logic functions, has also increased the arithmetic operations, data processing and transmission, communications and self-diagnostic capabilities. In the 1980's, the late, as ultra-large-scale integrated circuit technology is developing rapidly, microprocessor market a sharp price drop, the PLC makes the microprocessors used by the general improvement in grades. Furthermore, in order to further improve the processing speed of PLC, the manufacturer has developed a dedicated logic chip, greatly improving the PLC hardware and software functions.
2. Characteristics PLC
In the developed industrial countries, PLC has been widely used in all industrial sectors. According to "The United States market information" World PLC and software market report, in 1995 the global software PLC and its economies of scale of about 5 billion US dollars [5]. As electronic technology and the development of computer technology, the PLC functions are greatly enhanced, with the following characteristics:
(1) high reliability. PLC benefited from the high-reliability hardware and software on a series of anti-jamming measures and the cycle of its special scanning methods of work.
(2) with rich I / O interface module. PLC for different industrial field signal and the corresponding I / O modules and industrial devices or equipment at the scene of a direct connection. In addition to improving performance, it also has a variety of man-machine dialogue interface modules to the industrial composition of local area networks, it also multiple communications network interface module.
(3) modular structure. To meet the needs of various industrial control, in addition to a small PLC unit, the vast majority of PLC are modular structure. PLC various components, including the CPU, power supply, I / O, etc. is modular in design from the rack and cables will connect each module, the system's size and function in accordance with the needs of users of its own portfolio.
(4) easy to learn programming. Most of the PLC programming relay control circuit similar to the ladder diagram form, the user, do not have computer expertise, it is easy to general engineering and technical personnel understand and master.
(5) Installation is simple and easy maintenance. PLC does not require specialized equipment room in a variety of industrial environments can be directly run. Various modules are run and fault indication devices, user-friendly understanding of the operation and find fault. The modular structure, so any failure of a module, users can replace the module, allowing the system to rapidly resume operation.
Second, the characteristics and Application of industrial PC
1. Industrial PC industrial control applications
Industrial PC hardware and software support of a broad, diverse varieties can take full advantage of excellent graphical user interface capabilities, the industrial users an enormously attractive. Early PC but not suitable for industrial process control automation applications, such as increasing modified by strengthening the protection of the case, such as cooling damping taken measures to meet the industrial environment is the application of some of the requirements of the characteristics of its early development. In recent years, with the further integration of chips increase, the increase in functionality, system board technology, packaging components and surface mount technology improvements, and standard industrial bus, a standard operating system and graphical user interface software development, the Industrial PC development and application to enter its peak period, the complete machine reliability improved hardware, system software has continually improved, greatly enriched applications, in-depth industrial automation and control industries in various fields. According to incomplete statistics, in the industrial automation industrial PC usage in the total industrial control computer 65%, and an annual growth rate of 21 per cent continued to expand. PC manufacturing industry by buying rate of the PC market as a whole accounted for about 10 percent. In the industrial automation process control systems used in industrial management industry accounted for 44.1%, applied to the console operator of 36.4%, applied to the management of the quality of 18.8%, applied to monitor and control, engineers console, Data Acquisition System respectively of the total 18.2%, 12.6% and 11.1%.
Industrial PC A notable feature is independent of configuration, but also with the DCS, PLC, CNC and other computer connected network. At present, almost all DCS, PLC manufacturers use industrial PC control system preparation procedures, more and more companies use industrial control system operator interface PC as a workstation. Formed by the industrial PC computer control system in the field of industrial automation process control play a very important role, has been outstanding for factory and workshop level process control, data acquisition, batch processing, quality control, automation and machine optimization and experts control, and other tasks.
2. Main features of the PC industry
(1) an industry-standard application
In order to enable different computer manufacturers can be linked to one another, as well as take full advantage of the market varied PC components and the functions provided by the module, industrial PC with standard interface, which not only required by the IEEE, DIN and ISO standards, to adopt AT (ISA), EISA and STD, VME, Multibus Ⅱ, and other bus standards. Industrial PC now has been widely adopted PCI, PCMCIA bus standard, the two industry-standard bus for improved performance and speed of a PC great role.
(2) to take the necessary protection measures
Applications must be based on the control of environmental conditions on the PC industry adopt various protective measures, adapted from a project management departments to the scene operational control applications. Industrial PC must be able tolerance of the harsh conditions at the production environment, we must have good heat dissipation, ventilation, waterproof, dustproof, anti-jamming and anti-corrosion and anti-shock, anti-vibration and a series of protective features.
(3) industrial operating system
MS-DOS because of lack of memory, unable to support multi-task, the lack of real-time features networking capacity and poor, has been basically not used. Along with the main computer chip, the rapid development of higher speed and better performance of industrial PC endless. In addition, almost all software development companies have shifted the focus will be open to the OS / 2, Windows and Unix, and other operating systems. Especially suitable for industrial process control automation real-time multi-tasking operating system application of Windows NT/2000 PC industry has generally become the mainstream operating system.
(4) and automation equipment and communications systems
Industrial PC should be able to with a variety of automated equipment and systems for effective communication, such as PLC, DCS, data acquisition systems, as well as on a management computer communication. With the continuous development of new technologies, due to open systems and system integration technology for the development needs of the PC industry these communications will be increasingly important role in the show.
Standard communications network to the development of the industrial PC applications more open, and will enable its small computer pose a greater threat. MAP agreement to Ethernet-based communication networks to allow various computer systems communicate with each other directly. Different levels of automation in the mutual communication network systems, require separate handling of the communication channel. Industrial PC required monitoring level from the lower level data acquisition system and transmitted to a computer on.
(5) the safe operation of
In addition to the PC industry adopt various protective measures, the need for the operation of state industrial PC monitor, monitor the operation of computer systems and software, scheduled inspection procedures specified in the implementation of the cycle. Computer should be able to monitor the power supply, and failure or excessive deviation warning signal was issued.
2. Industrial PC the status quo and development trend
Industrial PC now have a wide range of performance and functionality, low-grade industrial PC with a CRT terminal operators, high-grade industrial workstation with a PC. Thus, high-grade and low-grade industrial PC workstation performance and the price of overlap, the difference is disappearing, industrial PC and workstations increasingly blurred the boundaries between.
Industrial PC workstation is the industrial automation process control system applications excellent choice, standard communication networks and the use of graphical operating system makes industrial PC and other equipment to effectively communicate. With 32-bit and 64-bit computer chips and the emergence of use, will be further enhanced industrial PC workstation functionality and performance, but also to a higher future direction.
Industrial PC software is in the process of industrial automation control system of a key application. Hardware performance and the improvement of the drop in prices, as well as standardization and greater efficiency, better graphics and the use of the operating system to promote industrial PC software is an important factor in development. At present, the rapid development of industrial PC software on the market has thousands of independent software development company can supply in the industrial PC running on industrial process control configuration software package to meet the rapid growth of the industrial user needs. Industrial PC application of industrial process control software packages are running on the configuration of OS / 2, Windows, and UNIX operating system standard. Industrial process control applications have emerged in large quantities, software development companies can provide a large number of industrial PC on the run for the PLC, DCS, such as industrial automation and control system configuration tools and graphical user interface software. Many PLC, DCS manufacturers development of the software configuration tool for automatic control system has become an important component. They used to replace dedicated industrial PC workstations, for the creation of real-time database, the control loop, graphic footage showed police records, real-time and historical trend data recording and process control, simulation, and other tasks. Now, for the process of surveillance and control, unit control, factory data collection, process optimization control, process control, simulation, statistical quality-control (SQC), the Statistical Process Control (SPC) and expert system for the control of industrial automation and control package has been tremendous developments. DAE applications such as IBM's software platform and the emergence of applications, the application provides a unified software development tool. Application Platform features from the PC-industry data exchange within the factory to the coordination of multiple systems, the standard data interface allows computer control equipment and exchange of data and information networks, for integrated information management and control system provides great convenience.
Along with the standard graphical operating system continuously improve and develop, process control and industrial automation package greatly enriched, the industrial PC applications will increasingly strong.
Three, the characteristics and Application of DCS
DCS since its birth, after decades of continuous improvement, development and modernization has been very mature. Compared with the early, the scale of their systems, control functions, and other areas have been tremendous developments in changes in the reliability, flexibility, adaptability, scalability, cost-effective integrated technical indicators have seen increased and improved. Has been widely used in petrochemical, pharmaceutical, energy, chemicals, paper, oil refining, metallurgy and food and beverage, and other industries, and has made very significant economic and social benefits. According to statistics, production facilities from analog instruments to DCS control the economic benefits can be achieved by the overall efficiency of 60%. DCS average payback period for 12, after the introduction of advanced control strategies can reduce the payback period of 0.5 to 1 year. DCS is today into various kinds of advanced control technology and equipment, and to the comprehensive integrated information management and automated process control systems, that is, CIMS direction.
1. Development process
From 1975, the DCS roughly experienced the 1975 ~ 1980, the first generation, from 1980 to 1985 the second generation, and after 1985 the third generation of three stages of development. Many manufacturers take DCS phased development strategy, adopted in the early systems continue to develop and improve, then launched with a variety of new features of the new system, the new system compatible with the original equipment homogeneous.
Early DCS storage capacity small, relatively simple function. System modules include process control, process interface modules, CRT operator station, control computer and data Highway, Part 5. Its characteristics are using microprocessors to achieve decentralized control, CRT operator station and the process control unit separation operation carried out on display and remote control configuration. Honeywell company TDC-2000 is the first generation of the representation of DCS products.
DCS mainly by second-generation local area networks, multi-function controllers, the computers, enhanced operator station, multifunction operator station, the connector between the network, system management module, and other components. Its characteristics are achieved more thoroughly decentralized control, decrease in the number of wiring, and anti-performance enhancement, improved level of standardization of hardware, high universality, function more comprehensive. Not only strengthened control, and strengthening the system-wide information management, the introduction of local area networks and fiber optic communications technology. During this period the representation of the company products include Honeywell TDC-3000 and Westinghouse WDPF systems.
DCS new generation is the most important feature of the process control, monitoring, management, scheduling organically integrate, through the use of open systems and standards such as MAP communication networks, such as Ethernet and Fieldbus solve different manufacturers equipment interconnection between issues. During the system is the development of a number of new features, using a 32 or 64-bit microprocessor, and a powerful workstations and enhanced the sequence control, volume control, the system can accommodate industrial PC and PLC; software greatly enriched by the standard graphical operating system platforms, and the user interface; introduction of the expert system, process control and other senior adaptive control function. Its products include Foxbor company representative I / A Series intelligent control system, ABB-Bailey INFI 90, ABB company Freelance 2000, RTP company RTP 2000/2200 HCS (Mixed Control System), and Yokogawa XL mXL, Honeywell Corporation TDC-3000 LCN / VCN-PM and Siemens PCS 7 systems.
2. New characteristics and new development
(1) Open to the DCS system to develop in the direction of CIMS
Along with the standard communication network and the development of fieldbus technology, a multi-level communications network DCS is the progressive realization of the full liberalization. The new system is the adoption of the ISO OSI model, the communication protocol to meet MAP / TOP or IEEE standards. In a backbone network, widely used MAP 3.0 agreement or ISO / OSI model; middle layer to use Mini MAP, IEEE 802.3, Ethernet or Proway; equipment is used at the lowest level fieldbus or bus to connect the transmitter. Open systems change the past DCS manufacturers self-contained closed situation, and make industrial users in the application of automation hardware and software have a greater choice.
DCS is the new generation of multi-level multi-regional development. With multi-level communication networks as a tool for the entire factory or enterprise information management and production control integration, the lowest level in the factory using digital equipment integrated into the scene DCS, in the solution of local senior management of various types of computer networks and interconnection, thus achieving optimal scheduling, decision-making, as well as the overall production process optimization. This production with the use of computer programs, product development, production processes and the material flow and information flow, integrated management system requirements for the development of CIMS. DCS use of open systems gradually to the direction of CIMS is integrated automation control system integrated a basic method.
(2) workstations and graphical user interface features strengthen the operating station
Workstations (including industrial PC workstations) and the use of graphical user interface, making recognizable DCS operator station. Many DCS manufacturers will be more DEC, SUN and companies such as Apollo Unix workstation tasks for the operator interface and control certain tasks, and corresponding use of the Motif, Penlook, X Window, OS / 2, Windows and other graphical user interface. Workstations cost-effective prices, high efficiency, and provides a user-friendly operator interface equipment. High-function workstations and high-resolution graphics equipment used, making operation to handle the greater amount of information, higher quality information processing, and use the mouse, touch screen, the cursor to the ball-type, as well as a number of other human-machine engineering.
(3) a 32 or 64-bit processor hardware performance improved
32 or 64-bit microcomputer development and use, is a milestone in the development of computer technology, the DCS hardware performance has a significant impact on the improvement. At present, most DCS has spent 32 or 64 computer to replace the original 16 aircraft, therefore, the corresponding process control stations and upgrade the operator stations. Series 86 using Intel processors Extended PC manufacturers now mainly uses the Pentium processor handling interface tasks while using M68 series producers are increasingly used in the 68020,68030 more processors. Most workstation processor performance to 5 ~ 50 M instructions / s. DCS process controllers use 32 or more processors, the performance increase than 2 times greater than before, the communication speed of the bus more than three times the network data transmission speed of 10,100,1000 Mb / s, the communications distance up to 20 km, I / O points up to 20,000 more, with the same scale system cheaper than the previous 30 to 40 percent.
(4) Enhanced batch processing capacity
Early DCS mainly used for process control, DCS batch processing function has continually increased, and more and show its importance. DCS use menu operation and fill in the blank approach to system configuration and graphics features are suitable for batch processing applications. DCS vast majority of new products use the same controller can achieve continuous and batch process control. DCS logic operation in the software, such as Boolean functions more functions, enhanced Sequence Control System and volume control. If ABB-Bailey INFI 90 system uses a batch-processing language Batch 90 automatic processing of documents and internal Chaxi capacity, and function codes, ladder diagram mixed use, it can be directly read and write functional code and ladder diagram, allowing the interlock logic Disconnect in the order of control logic for implementation, simplifies the batch processing logic implementation.
(5) software greatly enriched, an increase of senior control
In the operating system, Windows NT and Unix open systems as a representative of a broad development prospects, its features include multi-user, multi-tasking, good character and can be transplanted networking capabilities. At present, real-time industrial automation in the Unix process control system of the openness of the structure play an important role, with the exception of DCS manufacturers for the development of their own operating systems, Unix and Windows NT are in a variety of DCS in the most widely used standard operating system.
DCS configuration software modules used for the object-oriented language and the language of some system uses advanced programming language and graphics software. Configuration process normally use input and output, selection, calculation, logic, the police, limit the rate of order and control modules such as soft connections, a different control loop. Menu and fill in the blank-control operation makes configuration very easy.
DCS control algorithm is continuously improve and develop. Apart from achieving PID, nonlinear, feedforward, Cascade, feedforward and feedback, but also the sequence control logic control and the ladder diagram, and the self-tuning PID parameters set, adaptive control. DCS manufacturers for the provision of various software modules, such as SPC / SQC (statistical-process control / statistical quality-control), CAD, artificial intelligence and expert systems, greatly enriched the DCS software library, an increase of high-level control system , the senior now on the market has reached thousands of control packages. Expert System, multivariable predictive control, fuzzy logic control and artificial neural network technology has been gradually practical and commercialization.
DCS future software design and development will continue to focus on the following several aspects of the characteristics: modular program design, object-oriented programming; dedicated programming method used to achieve the X Window, voice recognition, etc., in order to industrial automation users provide more flexibility in the application of the operator interface.
(6) intelligent sensors and other digital equipment to enter the scene of DCS
At present, the industrial process control automation company has introduced a large number of microprocessors, have both analog and digital signal output, and digital communication capabilities of intelligent field instrument. DCS manufacturers are using a variety of methods of the digital field devices integrated into its own system. Honeywell IACD such as two-way communication system for intelligent transmitter and TDC-3000 process controller connections and other components; ABB-Pele two-way communication system using 9600 baud FSK physical layer transmission, including its hardware input Fieldbus Fieldbus modules and terminal unit, software management procedures, including the transmitter and the transmitter function block; Moore company Mycro HART door connector can support 256 point-to-point connections or over 480 points connected intelligent transmitter; Foxbro companies addition to its own digital equipment integrated into the scene intelligent I / O system, also provides more than 60 other manufacturers, connecting doors connector.
Fieldbus standard, from the bottom-up equipment to achieve the interconnection of different manufacturers, with the current technology development trend. At present, the development of fieldbus standard has been a high degree of international attention, is integrated industrial automation control system indispensable component. With the standardization of fieldbus communication technology development, the more intelligent DCS and control will shift downward, decentralized control equipment at the field level. They will DCS in the diagnosis and treatment provide a better platform, which enables more advanced DCS to open forms.
(7) DCS further accommodate industrial PC and PLC
Industrial PC and PLC equipment as the DCS is now very common. DCS overwhelming majority of manufacturers has been providing industrial PC, PLC to DCS network connected to the hardware interface and application software.
Industrial PC can make use of touch-screen and CRT window, a menu-driven approach may be to establish control strategy can also be used to achieve a plug on the motherboard and external communication. Through appropriate software and hardware interfaces, industrial PC with DCS in the process of connecting loop controller for loop control graphics. DCS industrial use as a PC operating station, programming terminals, surveillance, Taiwan, workstations, such as ABB-Pele, companies such as DCS Feixieer few years ago and the IBM PC compatible, DEC Professional, as well as 300 personal computers, etc. used for system configuration, monitoring, programming, and other tasks. Apart from some manufacturers developed a series of interface components and software, industrial PC as a DCS operator stations and other tasks, but also by third-party manufacturers such as OnSpec, and other process control packages.
The relationship between the PLC and DCS is not only combine, and compete. Most are now combining DCS ladder logic programming technology, all PLC increases the simulation module to deal with the continuous production process. PLC through structural improvements, communications and networking capacity and control functions to increase and the introduction of similar DCS operator station, with monitoring computer operator interface. DCS also continuously enhance and batch processing capabilities, a small-scale, high-functional, modular direction. Thus DCS and PLC are gradually move closer, the two boundaries become increasingly blurred. They are functional and application of mutual penetration and integration. Thus, in many applications, it is difficult to distinguish between what is the PLC, which is the DCS. DCS are generally of the PLC interface can be connected to the PLC in the DCS. At present, a PLC-based DCS developed very quickly, discrete manufacturing and process industries tend to use hybrid control strategy PLC / DCS. Some of the same chassis system will be continuous control and PLC logic function together, not a separate PLC systems, such as the United States RTP 2000/2200 by the HCS that way, the system will be complete PLC and DCS features integrated together with the application of a control strategy Configuration Software NetSuite can complete all the control functions in the design and configuration.
(8) Use of new technologies such as optical fiber communication
DCS in its development process and draw upon a variety of advanced technology. Optical fiber communications, high-density large-capacity disk surface mount technology, voice synthesis and recognition, multimedia, and other new technologies, as well as low-power CMOS RISC processor and other devices and has been in some of the new DCS has been fully applied. Optical fiber communications technology in the application of DCS more extensive. Because fiber is small in size, and large amounts of information, small signal attenuation and frequency bandwidth, anti-interference capability, transmission speed, the advantages of high reliability, high-speed access DCS used by the twisted pair and coaxial cable will gradually be replaced by fiber optic cable, making further enhance the effectiveness of communications systems. To further enhance system reliability, DCS communications bus network, as well as all levels of man-machine interface, controller interface at the scene and have been widely adopted redundant, fault-tolerant and fault isolation, and other protective measures.
3. DCS to the future direction of CIMS
DCS What is the future? A foreign process control experts to depict that image: DCS is disappearing, but the functions provided by the DCS will never disappear, they adapt to efficient, secure, real-time industrial process control automation needs of chassis control will continue to exist, but control room of the future will face enormous changes in the future, that the control room is more like a data processing center, large-scale conventional DCS operator console will become obsolete equipment in the DCS and senior management computer "seamless" multi-level connections information management system architecture system, the DCS as an independent entity phenomenon will disappear. In other words, the DCS will develop to a higher form of it.
PLC、工業PC與DCS的特點與趨勢
內容摘要：目前，廣泛應用于工業自動化系統的3大件是工業PC、DCS和PLC。在此，對于他們的經濟技術水平和發展趨勢進行敘述。
關鍵字：PLC PC DCS 自動化 趨勢
一、可編程序控制器的特點及應用
1. PLC的應用
早期的可編程序控制器(Programmable Logic Controller，PLC)，主要用來代替繼電器實現邏輯控制。隨著計算機技術、通信技術和自動控制技術的迅速發展，可編程序控制器將傳統的繼電器控制技術與新興的計算機技術和通信技術融為一體，具有可靠性高、功能強、應用靈活、編程簡單、使用方便等一系列優點，以及良好的工業環境工作性能和自動控制目標實現性能，在工業生產中得到了廣泛的應用。
1969年，美國數字設備公司(DEC)研制出世界上第一臺可編程控制器。早期的可編程控制器由分離元件和中小規模集成電路組成，主要功能是執行原先由繼電器完成的順序控制、定時等。70年代初期，體積小、功能強和價格便宜的微處理器被用于PLC，使得PLC的功能大大增強。在硬件方面，除了保持其原有的開關模塊以外，還增加了模擬量模塊、遠程I/O模塊和各種特殊功能模塊。在軟件方面，PLC采用極易為電氣人員掌握的梯形圖編程語言，除了保持原有的邏輯運算等功能以外，還增加了算術運算、數據處理和傳送、通訊、自診斷等功能。進入80年代中、后期，由于超大規模集成電路技術的迅速發展，微處理器的市場價格大幅度下跌，使得PLC所采用的微處理器的檔次普遍提高。而且，為了進一步提高PLC的處理速度，各制造廠商還研制開發了專用邏輯處理芯片，大大提高了PLC軟、硬件功能。
2. PLC的特點
在發達工業國家，PLC已經廣泛的應用在所有的工業部門。據“美國市場信息”的世界PLC以及軟件市場報告稱，1995年全球PLC及其軟件的市場經濟規模約50億美元[5]。隨著電子技術和計算機技術的發展，PLC的功能得到大大的增強，具有以下特點：
(1)可靠性高。PLC的高可靠性得益于軟、硬件上一系列的抗干擾措施和它特殊的周期循環掃描工作方式。
(2)具有豐富的I/O接口模塊。PLC針對不同的工業現場信號，有相應的I/O模塊與工業現場的器件或設備直接連接。另外為了提高操作性能，它還有多種人機對話的接口模塊；為了組成工業局部網絡，它還有多種通訊聯網的接口模塊。
(3)采用模塊化結構。為了適應各種工業控制需要，除了單元式的小型PLC以外，絕大多數PLC均采用模塊化結構。PLC的各個部件，包括CPU、電源、I/O等均采用模塊化設計，由機架及電纜將各模塊連接起來，系統的規模和功能可根據用戶的需要自行組合。
(4)編程簡單易學。PLC的編程大多采用類似于繼電器控制線路的梯形圖形式，對使用者來說，不需要具備計算機的專門知識，因此很容易被一般工程技術人員所理解和掌握。
(5)安裝簡單，維修方便。PLC不需要專門的機房，可以在各種工業環境下直接運行。各種模塊上均有運行和故障指示裝置，便于用戶了解運行情況和查找故障。由于采用模塊化結構，因此一旦某模塊發生故障，用戶可以通過更換模塊的方法，使系統迅速恢復運行。
二、工業PC
1. 工業PC的工業控制應用
工業PC具有廣泛軟硬件支持特性，品種豐富多樣，能充分利用優良圖形用戶界面功能，對工業用戶有巨大吸引力。但早期PC不適合工業自動化過程控制應用，通過加固改裝如增加保護機殼、采取減振降溫等措施，滿足工業環境應用的一些要求是其初期發展的特點。近年來，隨著芯片集成度的進一步提高，功能增加，制板工藝、元器件封裝和表面安裝技術的改進，及標準工業總線、標準操作系統和圖形用戶界面軟件的發展，工業PC的發展和應用進入鼎盛時期，整機硬件可靠性提高，系統軟件不斷完善，應用軟件極大豐富，深入工業自動化控制行業各個領域。據不完全統計，工業PC在工業自動化中的使用率占全部工業控制計算機的65%，且每年以21%的增長速度繼續擴大。制造業購買的工業PC按金額計算占整個PC市場10%左右。在工業自動化過程控制系統行業應用于工業管理的占44.1%，應用于操作員控制臺的占36.4%，應用于質量管理的占18.8%，應用于監視和控制、工程師控制臺、數據采集系統的分別占總數的18.2%、12.6%和11.1%。
工業PC的一個顯著特點是可獨立組態，也可與DCS、PLC、CNC和其他計算機連成網絡。目前，幾乎所有DCS、PLC生產制造商都采用工業PC編制控制系統程序，越來越多控制系統公司采用工業PC作為操作員界面工作站。由工業PC所組成的計算機控制系統在工業自動化過程控制領域發揮了十分重要的作用，已出色地用于工廠和車間級過程控制、數據采集、批量處理、質量管理、機床自動化以及優化和專家控制等任務。
2. 工業PC的主要特點
(1)工業標準的應用
為了使不同廠家生產的計算機能相互連接，也為充分利用市場上多種多樣PC元件和模塊所提供的功能，工業PC采用了標準接口，它不僅需采用IEEE、DIN和ISO等標準，還需采用AT(ISA)、EISA及STD、VME、MultibusⅡ等總線標準。現在工業PC已廣泛采用了PCI、PCMCIA總線標準，這兩種標準總線對于提高工業PC性能和速度有極大推動作用。
(2)采取必要的保護措施
必須根據控制應用的環境條件對工業PC采取各種保護性措施，使之適合于從工程管理部門到現場操作控制的應用。工業PC必須要能耐受條件惡劣的現場生產環境，必須具備良好的散熱、通風、防水、防塵、抗干擾、抗腐蝕、防沖擊、抗振動等一系列保護性特點。
(3)采用工業操作系統
MS-DOS因內存不足，無法支持多任務，缺乏實時性功能，連網能力差等缺點，目前已基本不采用了。隨著計算機主芯片的飛速發展，更高性能和更高速度的工業PC層出不窮。另外，現在幾乎所有軟件開發公司都已將開放重點轉移到OS/2、Windows和Unix等操作系統上。尤其是適合于工業自動化過程控制系統實時多任務操作應用的Windows NT/2000已經普遍成為工業PC的主流操作系統。
(4)與自動化設備和系統的通信
工業PC須能與各種自動化設備和系統進行有效通信，如與PLC、DCS、數據采集系統以及上一級管理計算機的通信。隨著新技術的不斷發展，由于系統開放和系統集成技術的發展需要，工業PC的這些通信功能將會越來越顯示出其重要作用。
標準通信網絡的發展使工業PC的應用更開放，并能使它對小型計算機構成更大威脅。以MAP協議為基礎的Ethernet通信網絡允許各種計算機系統間直接相互通信。在不同級別自動化網絡系統間相互通信時，則需單獨處理各通信信道。監控級工業PC則需從下級系統采集數據信息，并傳送到上一級計算機。
(5)安全操作特性
除了對工業PC采取各種保護性措施以外，還需要對工業PC的操作狀態進行監視，監視計算機的運行及其軟件系統，檢查具體程序在預定周期內的執行情況。計算機應能監視電源電壓，并在故障或偏差過大時發出報警信號。
3. 工業PC的現狀及發展趨勢
工業PC現在具有各種各樣的性能和功能，低檔工業PC與CRT操作終端相當，高檔工業PC可與工作站相當。因此，高檔工業PC與低檔工作站的價格和性能重疊，差別正在消失，工業PC與工作站之間的界限越來越模糊。
工業PC工作站是工業自動化過程控制系統應用的優良選擇，標準通信網絡和圖形化操作系統的采用使得工業PC與其他設備能有效地進行通信。隨著32位和64位計算機芯片的出現和使用，將會進一步提高工業PC工作站的功能和性能，今后還會向更高方向發展。
軟件是工業PC在工業自動化過程控制系統中應用的關鍵。硬件性能的提高和價格的下降，以及標準化和功效更強、更好圖形化操作系統的采用是促進工業PC軟件發展的重要因素。當前，工業PC軟件發展迅速，市場上已有數千家獨立軟件開發公司能供應在工業PC上運行的工業過程控制組態軟件包，以滿足急速增長的工業用戶需要。工業PC上應用的工業過程控制組態軟件包大多運行在OS/2、Windows和UNIX等標準操作系統上。工業過程控制應用軟件大批量涌現，軟件開發公司提供了大量可在工業PC之上運行，用于PLC、DCS等工業自動化控制系統的組態工具和圖形化人機界面軟件。許多PLC、DCS生產制造商開發的組態工具軟件已成為其自動化控制系統的重要組成部分。他們采用工業PC代替專用工作站，用于建立實時數據庫、控制回路、圖形畫面顯示、報警記錄、實時和歷史數據趨勢記錄以及過程控制仿真等任務。現在，各種用于過程監視與控制、單元控制、工廠數據采集、過程優化控制、過程控制仿真、統計式質量控制(SQC)、統計式過程控制(SPC)以及專家系統控制的專用工業自動化控制軟件包都有了巨大發展。IBM公司DAE等應用平臺軟件的出現和應用，為應用軟件開發提供了統一工具。應用平臺功能可從工業PC機間的數據交換到工廠范圍內多個系統的協調，其標準數據接口允許計算機、控制設備和網絡間互換數據信息，這些為集成信息管理與控制系統提供了極大方便。
隨著標準圖形化操作系統的不斷完善和發展，以及工業自動化過程控制軟件包的極大豐富，工業PC的應用必將日益旺盛。
三、 DCS
DCS自誕生以來，經過幾十年的不斷改進、發展和更新換代，已相當成熟。與初期相比，其系統規模、控制功能等各方面都有了巨大發展變化，在可靠性、靈活性、適應性、擴展性、性價比等綜合技術指標方面都有了很大提高和改善。目前已廣泛應用于石化、制藥、能源、化工、造紙、煉油、冶金及食品飲料等工業，并已取得極為顯著的經濟和社會效益。據統計，生產裝置由模擬控制儀表改為DCS所取得的經濟效益可占整體效益的60%。DCS投資回收期平均為一兩年，采用高級控制策略后可使投資回收期縮短0.5～1年。當今DCS正在融入各種先進控制技術與設備，并全面向集成化信息管理與自動化過程控制系統，即CIMS方向發展。
1.發展歷程
從1975年以來，DCS大致經歷了1975～1980年的第一代，1980～1985年的第二代，以及1985年以后的第三代3個發展階段。許多生產廠家的DCS采取階段性發展策略，通過對早期系統不斷發展和改進，進而推出具有各種新特點的新系統，新系統與原設備均相兼容。
早期DCS存儲容量小，功能較簡單。系統主要包括過程控制單元、過程接口單元、CRT操作站、監控計算機和數據公路等5部分。其特點是采用微處理器實現分散控制，CRT操作站與過程控制單元分離，進行集中顯示操作和遠程控制組態。Honeywell公司TDC-2000是第一代DCS的代表性產品。
第二代DCS主要由局部網絡、多功能控制器、主計算機、增強型操作站、多功能操作站、網間連接器、系統管理模件等組成。其特點是實現了更徹底的分散控制，接線數量減少，抗干擾性能增強，硬件標準化程度提高，通用性強，功能更全面。不僅增強了控制功能，且加強了全系統信息管理，引入了局部網絡和光纖通信技術。這一時期的代表性產品包括Honeywell公司TDC-3000和西屋公司WDPF等系統。
新一代DCS最重要的特點是把過程控制、監視、管理調度有機結合起來，通過采用開放系統和標準通信網絡如MAP、Ethernet及現場總線等，解決了不同生產廠家設備間的互連問題。其間的系統具有若干新的發展特點，采用了32或64位微處理器和功能強大的工作站，增強了順序控制、批量控制能力，系統能容納工業PC和PLC；軟件極大豐富，采用了標準圖形化操作系統平臺，統一了用戶界面；引入了專家系統、自適應過程控制等高級控制功能。其代表性產品包括Foxbor公司I/A系列智能化控制系統、ABB-貝利INFI 90、ABB公司Freelance 2000、RTP公司RTP 2000/2200 HCS(混合型控制系統)、橫河XL和mXL、Honeywell公司TDC-3000 LCN/VCN-PM以及西門子PCS 7等系統。
2. 新特點和新發展
(1)全開放系統使DCS向CIMS方向發展
隨著標準通信網絡和現場總線技術的發展，采用多級通信網絡的DCS正逐步實現全面開放。新系統都采用ISO開放系統互連模型，通信協議滿足MAP/TOP或IEEE標準要求。在主干網絡一層，廣泛采用MAP 3.0協議或ISO/OSI模型；中間層多采用Mini MAP、IEEE 802.3、Ethernet或Proway；最低層現場設備則采用現場總線或變送器總線進行連接。開放系統改變了以往DCS生產廠家自成一體的封閉局面，并使得自動化工業用戶在應用軟硬件方面有更大選擇余地。
新一代DCS正在向多級多區域化方向發展。它以多級通信網絡為工具，把整個工廠或企業的生產信息管理和控制相互結合起來，在工廠最低層采用數字方式把現場設備集成到DCS之中，在高層解決局部網絡及各類管理計算機的互連，從而實現最優調度、決策，以及生產過程總體優化。這就符合利用計算機對生產計劃、產品開發、生產過程及有關物質流和信息流進行綜合管理CIMS系統的發展要求。利用DCS開放系統逐步向CIMS方向推進，是綜合自動化控制系統實現集成的一種基本方法。
(2)工作站和圖形用戶界面強化了操作站功能
工作站(包括工業PC工作站)和圖形用戶界面的采用，使得DCS操作站面貌一新。許多DCS生產廠家更多地將DEC、SUN及阿波羅等公司的Unix工作站用于操作員界面任務及其某些控制任務，并相應采用了Motif、Penlook、X窗口、OS/2、Windows等圖形用戶界面。工作站價格合算、效率高，并提供了對用戶友好的操作員界面設備。高功能工作站和高分辨率圖形設備的采用，使得操作站處理的信息量更大，信息處理質量更高，并能利用鼠標器、觸摸屏、轉球式光標以及其他一些人機工程技術。
(3)采用32或64位處理器提高硬件性能
32或64位微機的發展和使用，是計算機技術發展的里程碑，對DCS硬件性能的提高具有重大影響。目前，大多數DCS已經用32或64位微機取代了原16位機，因此，相應的過程控制站和操作員站功能升級。采用Intel 86系列處理器的擴展型PC生產廠家現在主要采用Pentium處理器處理操作員界面任務；而采用M68系列的生產廠家則越來越多地采用了68020、68030以上的處理器。大多數工作站處理器的性能達到了5～50M指令/s。DCS過程控制器采用32位以上處理器后，各項性能均比以前提高2倍以上，總線內通信速度提高了3倍以上，網絡數據信息傳輸速度達到10、100、1000Mb/s，通信距離可達20km，I/O點數可達20000以上，而同等規模系統卻比以前便宜了30～40%。
(4)增強批處理能力
早期DCS主要用于連續過程控制，現在DCS批量處理功能不斷增強，并越來越顯示出其重要性。DCS采用菜單操作和填空方式進行系統組態及其圖形顯示等特點都適合批量處理應用。絕大多數DCS新產品都能用同一控制器實現連續和批量過程控制。DCS軟件庫中邏輯運算、布爾函數等功能的增加，增強了系統順序控制和批量控制能力。如ABB-貝利INFI 90系統采用的批量處理語言Batch 90具有文件自動處理和內部查錯能力，可與功能碼、梯形圖混合使用，可直接讀寫功能碼和梯形圖，允許從聯鎖邏輯中所斷開的順序控制邏輯連續執行，簡化了批量處理邏輯的執行。
(5)軟件極大豐富，增加了高級控制功能
在操作系統方面，Windows NT和Unix作為開放系統的代表，具有廣闊發展前景，其特點包括多用戶、多任務、優良的可移植特性和網絡功能。目前，實時Unix在工業自動化過程控制系統結構的開放性方面發揮了重要作用，除DCS生產廠家自行開發的專用操作系統外，Unix和Windows NT是在各種DCS中使用最為廣泛的標準操作系統。
DCS組態軟件多采用功能模塊語言和面向對象的語言，有些系統采用高級程序設計語言和圖形化軟件。組態過程通常利用輸入、輸出、選擇、計算、邏輯、報警、限幅、順序和控制等模塊的軟連接，構成各種不同控制回路。菜單和填空式操作使得控制組態非常方便。
DCS控制算法正不斷完善和發展。除可實現PID、非線性、前饋、串級、前饋加反饋外，還可實施順序控制和梯形圖邏輯控制，及PID參數的自整定、自適應控制。DCS廠家提供的各種專用軟件模塊，如SPC/SQC(統計式過程控制/統計式質量控制)、CAD、人工智能和專家系統等，極大豐富了DCS軟件程序庫，增加了系統高級控制功能，現在市場上的高級控制軟件包已達數千種。專家系統、多變量預測控制、模糊邏輯控制及人工神經網絡等技術已逐步實用化和商品化。
今后的DCS軟件設計和開發仍將繼續突出以下幾個方面的特點：模塊化程序設計；面向對象程序設計；將專用程序設計方法用于實現X窗口、聲音識別等方面，以便為工業自動化用戶提供更加靈活適用的操作員界面。
(6)智能化傳感器等數字化現場設備進入DCS
目前，各工業自動化過程控制公司已推出大量采用微處理器、具備模擬和數字兩種信號輸出，并具有數字通信功能的智能化現場儀表。DCS生產廠家正在利用各種方法把數字化現場設備集成到自己的系統中。如Honeywell IACD雙向通信系統用于智能變送器與TDC-3000過程控制器等部件的連接；ABB-貝利雙向通信系統利用9600 baud頻移鍵控物理層傳輸方式，其硬件包括現場總線輸入模件和現場總線終端單元，軟件包括變送器管理程序和變送器功能塊；Moore公司Mycro HART門接器可支持256個點對點連接或480個多點連接的智能變送器；Foxbro公司除采用數字方式把自己的現場設備集成到智能化I/O系統外，還提供了60多種連接其他生產廠家的門接器。
采用標準現場總線，從底向上實現不同生產廠家設備互連，符合當前技術發展潮流。目前，現場總線標準的發展已受到國際高度重視，是綜合工業自動化主控系統不可缺少的組成部分。隨著標準化現場總線通信技術的發展，DCS中更多的智能和控制功能將向下轉移，下放到現場級控制設備。它們將為DCS的診斷和處理提供更好的平臺，使DCS走向更加高級的開放形式。
(7)DCS進一步容納工業PC和PLC
工業PC和PLC作為DCS中的設備現在已經非常普遍。絕大多數生產廠家的DCS都提供了把工業PC、PLC連入到DCS網絡系統的硬件接口和應用軟件。
工業PC可利用觸摸屏和CRT窗口技術，可采用菜單驅動方式建立起控制策略，還可利用母板上的插件實現與外部的通信。通過適當軟件和硬件接口，工業PC可與DCS中的過程回路控制器相連接，用于回路控制的圖形顯示。DCS利用工業PC作為操作站、編程終端、監視臺、工作站等，如ABB-貝利、菲歇爾等公司的DCS數年前就已把IBM PC及其兼容機，以及DEC Professional 300等個人計算機用于系統組態、監控、編程等任務。還有一些生產廠家除自己開發一系列接口部件和軟件，將工業PC作為DCS操作員站及其他任務以外，還可采用第三方生產廠家的如OnSpec等過程控制軟件包。
PLC與DCS的關系是既相結合、又相競爭。現在大多DCS都結合梯形邏輯程序設計技術，所有PLC都增加了模擬模件，以便處理連續生產過程。PLC通過結構改進，通信和連網能力增強，控制功能增加，并采用了類似DCS操作站、帶監控計算機的操作員界面。而DCS也在不斷增強批量處理能力，向小型、高功能、模塊化方向發展。因此DCS和PLC正逐漸靠攏，兩者界線變得越來越模糊。它們在功能和應用方面正互相滲透，相互融合。因而，在許多應用場合下，很難分清哪些是PLC，哪些是DCS。DCS一般都有對PLC的接口，可把PLC連接到DCS中。目前，以PLC為基礎的DCS發展很快，離散制造業和過程工業都傾向于采用混合控制策略的PLC/DCS。有的系統則利用同一機箱將連續控制和PLC邏輯功能結合在一起，不必采用單獨PLC系統，如美國RTP 2000/2200 HCS即采用了該方式，該系統完整地將PLC和DCS功能特性集成在一起，應用同一套控制策略組態軟件NetSuite就能完成所有控制功能的設計和組態。
(8)采用光纖通信等新技術
DCS在其發展過程中不斷吸取了各種先進技術。光纖通信、高密度大容量磁盤、表面安裝工藝、聲音合成與識別、多媒體等新技術，以及低功耗CMOS器件和RISC處理機等已在一些新的DCS中得到了充分應用。光纖通信技術在DCS中的應用越來越廣泛。由于光纖具有體積小、信息容量大、信號衰減小、頻帶寬、抗干擾能力強、傳輸速度快、可靠性高等一系列優點，DCS高速通道所采用的雙絞線和同軸電纜將逐漸被光纖電纜所代替，使得系統通信效能進一步提高。為進一步提高系統可靠性，DCS通信總線、網絡以及各級人機接口、控制器和現場接口等均已普遍采用冗余、容錯以及故障隔離等保護性措施。
3. DCS的未來是向CIMS方向發展
DCS的未來是什么？一個國外過程控制專家曾形象地描繪認為：DCS正在消失，但DCS所提供的功能將永遠不會消失，它們適應高效、安全、實時工業自動化過程控制的需要；控制機箱還將繼續存在，但是未來控制室的面貌將發生巨大變化，將來的控制室更像是一個數據處理中心，常規大型DCS操作員控制臺必將成為過時的設備；在DCS與上級管理計算機“無縫”連接的多級信息管理系統結構體系中，DCS作為獨立實體的現象將會消失。也就是說，DCS將會發展到它的更高形式。
...
文檔留言
