外文翻譯--基于plc監(jiān)控應(yīng)用平臺的發(fā)展

1、<p><b>　　英文原文</b></p><p>　　Development of a monitoring and control platform for PLC-based applications</p><p>　　S. Da'na, A. Sagahyroon , A. Elrayes, A.R. Al-Ali, R. Al-Aydi

2、</p><p><b>　　Abstract</b></p><p>　　This paper discusses the design and implementation of a platform to remotely monitor and control PLC-based processes over TCP/IP or by usingthe GSM

3、 network. The platform is built using industry-standard off-the-shelf PLCs. Integrated with each PLC are communication processors that canbe used for connectivity to the network and to a GSM modem. The communication proc

4、essor module (Ethernet module) used in this work, providesan industrial compatible protocol over TCP/IP that achieves the same functi</p><p>　　© 2007 Elsevier B.V. All rights reserved.</p><p&

5、gt;　　1. Introduction</p><p>　　The recent growth of networks technology and specially thewide spread of the Internet have promoted the development ofdistributed measurement systems for a variety of industrial

6、 applications.These distributed measurement systems can be used in the monitoring and control of various instruments in thenetwork [1,2].</p><p>　　A Programmable Logic Controller (PLC) is microprocessorbased

7、control system that can be programmed to sense, activateand control industrial equipment and therefore incorporates anumber of input/output terminals for interfacing to an industrial process. A control program stored in

8、the PLC memory determines the relationship between the inputs and outputs of the PLC. PLCs are intelligent automation stations that possess highly useful and desirable features such as [3]:</p><p>　　? Robust

9、ness.</p><p>　　? High degree of scalability: modern PLC families have a wide spectrum of CPU types that allows easy scalability in functionality and performance.</p><p>　　? Extensibility: the mo

10、dular design of PLCs enables the extension with a wide range of digital and analog I/O modules. Also, various integrated technology modules are available for various application areas.</p><p>　　? Sophisticat

11、ed communication capabilities: modern PLCs have communication ports that provide for centralized or distributed connectivity.</p><p>　　? Powerful development environment: modern PLC families come with a cros

12、s development environment that support different languages for programmability, allows semigraphical hardware configuration and offer strong debugging mechanisms.</p><p>　　Remote access to control and monito

13、r various devices in an industrial setting is of value to engineers and automation facilities. Current implementations of remote PLC monitor and control use dedicated PCs or web servers connected to the PLC. Fig. 1 illus

14、trates a common architecture used in industry. As shown, PLCs are connected to the network through a computer. The PLC system is usually interfaced to this computer using the serial Port or Profibus. These types of syste

15、ms are disadvantaged by t</p><p>　　In recent years and due to the ever increasing capabilities of PC computing and the influx of network protocols and standards, there has been a surge in the design and impl

16、ementation of distributed measurement and control systems for industrial applications. Typically, these systems are based on the clientserver architecture while securing communication using the TCP/IP protocol [4–6]. Mod

17、ern PLCs come with embedded web servers that provide open access to useful real time information and diagnos</p><p>　　In this paper we will discuss the design and implementation of a networked platform for r

18、emotemonitoring and control of PLCs. The platformis built around the Siemens S7 series of PLCs. These PLCs have an integrated communication processor that can be used to provide accessibility to the internet. The monitor

19、ing and control can be accomplished in a wired or wireless environment, via an intranet or internet hence providing for a complete solution for the remote monitoring and control of industrial</p><p>　　The pa

20、per is organized as follows: in Section 2 we describe the overall system architecture; section three includes a discussion of the software aspects of the system. Sections 4 and 5 present the communications methodology fo

21、llowed in this project and thepaper is concluded in Section 6.</p><p>　　Fig. 1. PC-based remote accessibility.</p><p>　　2. System architecture</p><p>　　The proposed system architect

22、ure is illustrated in Fig. 2.</p><p>　　The system consists of the following components:</p><p>　　? Simatic S7 200/300 PLC systems and Communication Processors (CPs). Each CP has an integrated co

23、mmunication interface (hardware and software) that allows the PLC to communicate in a LAN, WAN or via a GSM network.</p><p>　　? Clients and administrator are connected to the process via the network (or wire

24、lessly). Privileges can be set or reset by administrators to allow for or to limit the various clients' options.</p><p>　　? A Database Server connected to the process via the network for data logging and

25、 event recording.</p><p>　　? A variety of network options including GSM-based accessibility.</p><p>　　The PLC system Ethernet module is a communication processor for the S7 family used to connec

26、t the PLC to the network. An additional communication processor is used to allow communication between the PLC and the GSM modem over the serial port (RS232).</p><p>　　In the proposed implementation, the PLC

27、 system reports remotely the status of the process to the Database Server. The Database Server records the status of the PLC in time-based tables and performs any required data analysis. The system also receives and exec

28、utes commands from administrators and clients to control the process. GSM connectivity is also implemented to allow users with different privileges to access the status of the mandatory functions of the PLC and allow the

29、m to control thesefun</p><p>　　The System software was implemented mainly using Simatic Manager [7] and Java. The Simatic Manager environment is used for communication with the PLC system. The proposed archi

30、tecture allows for programming, reprogramming, and configuring the system remotely.</p><p>　　The Java application is developed using the S7-APIs (S7-Application Programming Interfaces) to establish the commu

31、nication between the Database Server and PLC station [8]. For example, using these APIs, we can instantiate objects that will connect theDatabase Server to the PLC station by specifying the IP Address and the S7 address

32、of the CPU contained in the PLC unit.</p><p>　　The PLC is connected to the process sensors and actuators using I/O modules.</p><p>　　After the Java application running on the server side establi

33、shes the connection to PLC using the S7-APIs, it then uses the Java Database Connector Technology (JDBC) to store the retrieved data that reflects the status of various PLC parameters in the Database Tables. JDBCis a tec

34、hnology that allows Java to connect to Database servers. It contains the required Java libraries that include all the necessary methods required to connect to the Database Server and execute SQL statements.</p>&l

35、t;p>　　The overall system allows users to set process values using the PLC. For example, users can set an output (actuate a motor) or change the value of a memory cell (memory bit, byte, word, flag, etc.). The system e

36、nvironment also provides for obtaining the readings of input values (sensors' readings) as well as capturing the status of the PLC. A Chart plotter can be used to convert readings fromthe PLCs into charts. An error r

37、eporting mechanism that provides administrators with useful diagnostic in</p><p>　　Fig. 2. System architecture.</p><p>　　3. System software architecture</p><p>　　The systems' so

38、ftware used in this project is divided into three components:</p><p>　　? A database management system</p><p>　　? Application modules (data manipulation modules, PLC communication modules and GSM

39、 modem modules)</p><p>　　? A user interface.</p><p>　　Fig. 3 depicts the systems' software major components and the directions of communication between them. A description of each component

40、is provided in the following subsections.</p><p>　　3.1. An overview of the database system</p><p>　　The database was created using Oracle 9i. It consists of a set of inter-related tables. Fig. 4

41、 illustrates the database schema used in this work. For the sake of brevity a brief description of each table is provided below:</p><p>　　? A Station table that contains the entire information associated wit

42、h the PLC such as station IP address, station name, etc.</p><p>　　Fig. 3. System software components.</p><p>　　Fig. 4. Database tables relationships.</p><p>　　? A Pointers table tha

43、t contains information about each Input, Output or, Memory that the system is using. Pointers represent addresses for Input, Output or, Memory.</p><p>　　? A Pointers reading table used to store the values re

44、ad from items pointed to by the various pointers. This table is similar to a log table that holds the various stations activities.</p><p>　　? An Admin table contains all the information on system users. A Ra

45、nk attribute indicates the security level for each administrator, such as, Main Admin, Supervisor, and Trainee. Additional information include login name, password, a Hint attribute for password recovery, etc.</p>

46、<p>　　? A Client table contains all the information pertaining to each client that is using the system such as user identification, password and phone.</p><p>　　? Admin_PLC and Client_PLC tables used t

47、o set the corresponding admin or client to a specific station id, and pointer id.</p><p>　　3.2. Application modules</p><p>　　Thesemodules are at the heart of the software components of the overa

48、ll system. They manage the communication between the user interface and the DBMS. They initiate the connection to the PLC system and contain the needed objects for GSM communication.</p><p>　　The application

49、 modules consist of following three submodules:</p><p>　　Fig. 5. A GUI display.</p><p>　　? A data manipulation module: this module has several classes that are called from within the user interf

50、ace (GUI) to perform various data manipulation tasks within the database such as: insert, update, and delete. For example, the insert class is responsible of inserting any new data received through the user interface.<

51、;/p><p>　　? A PLC communication module: this module consists of three classes; they are used to perform tasks such as accepting stations ID from users, verifying that each station has a pointer associated with

52、it, establishing connection to the PLC station, etc.</p><p>　　? A GSM module: this module provides for the communication between the GSM modem and the communication ports. The java communication package is u

53、sed. This package allows java to recognize both the serial and the parallel ports that are part of the system. It contains the necessary functions required to send and receive AT commands and SMS messages through the GSM

54、 modem.</p><p>　　3.3. The user interface</p><p>　　The user interface used in this work allows users (administrators and clients) to access and manipulate the database tables and to issue basic c

55、ontrol commands to the different PLC stations. For database manipulation the administrator depending on his/her rank can insert, update, or perform different queries. Administrators can also perform other activities usin

56、g this GUI such as sending SMS massages to different clients and administrators. Depending on his or her rank, an administrator can ente</p><p>　　Fig. 5 shows one of the GUI screens of the system. The figure

57、 shows the different fields that correspond to the station table attributes. Users can enter various values pertaining to a particular station such as its IP address, its location, number of inputs and maximum number of

58、outputs. As shown on the left panel of the GUI interface, users have the ability to search, view, configure, and update the information of a particular station. Fig. 5 depicts a GUI screen for the Update command. Users &

59、lt;/p><p>　　4. Using TCP/IP to communicate with the PLC</p><p>　　The CP module is a communication processor for the S7 family that allows PLCs to connect to an Intranet or the Internet in any LAN s

60、etup. The module supports the following TCP/IP communication services [7]:</p><p>　　? Secure FTP (File Transfer Protocol) and HTTP (Hyper Text Transfer Protocol) server login with user IDs and password</p

61、><p>　　Fig. 6. Sample GUI display. </p><p>　　Fig. 7. Response screen to a “Station Search”.</p><p>　　? Send E-mail messages with embedded PLC data to standard SMTP mail server</p>

62、;<p>　　? FTP client services for file transfer to a remote server</p><p>　　? FTP server services for file transfer to/from an internal 8 MB flash memory file system by a remote FTP client</p>&

63、lt;p>　　? HTTP server services for remote Internet browser access</p><p>　　? S7 series program instructions for Internet communication.</p><p>　　In addition the module also has the following f

64、eatures:</p><p>　　? Communication based on TCP/IP and ISO standards</p><p>　　? Factory installed MAC address</p><p>　　? Peer-to-peer communication capabilities with other S7 devices

65、</p><p>　　? Multiple (up to 8) connections</p><p>　　? Ethernet client or server configuration options</p><p>　　? Program instructions for initialization, reconfiguration, and data t

66、ransfer.</p><p>　　A PLC can be programmed locally or remotely to sense, activate and control industrial equipment and therefore, incorporates a number of input/output terminals that are used to interface the

67、 PLC to the environment or process. Each input and output connection point on a PLC module has a unique address that identifies it. Using the TCP/IP protocol, the IP address of the PLC, command type and the address of th

68、e item (I/O point) that is referenced are all contained in the IP packet. The IP address of</p><p>　　The Memory Parameters field contains information, such as the address of the item to be monitored and/or c

69、ontrolled. This item can be any of the following:</p><p><b>　　? Input</b></p><p><b>　　? Output</b></p><p>　　? Memory area</p><p>　　? Data block.

70、</p><p>　　It also contains other parameters such as data type (Boolean, integer, etc.), bit or byte offsets and so on.</p><p>　　Fig. 8. Frames used to communicate with the PLC system using TCP/I

71、P.</p><p>　　The Command Type field contains any of the following commands:</p><p>　　? Set Value</p><p>　　? Get Value</p><p>　　? Get Status.</p><p>　　The St

72、atus field of the frame returns the status of the addressed item. The value field contains the value of the addressed item.</p><p>　　Fig. 9. Messaging format for the Query frame.</p><p>　　5. GSM

73、 accessibility</p><p>　　Foreseeing the potential of GSM services for low volume data transmission and acquisition [9–11] we decided to incorporate these services in our system. The idea here is allow adminis

74、trators and clients to access the PLC system via the GSM network if needed, and also to be able to retrieve vital status information through it. The Java communication package was used to allow for the communication betw

75、een the GSM modem and the various ports of the PLCs and the server. For the GSM modem that is con</p><p>　　Fig. 10. Messaging format for the Response frame.</p><p>　　A brief description of the v

76、arious fields included in the above frame is given below.</p><p>　　Type of Frame (TOF): this is a 1 byte field. The user (administrator or customer) should know what type of frame he/she is sending. For the

77、query frame, the “Type of Frame” field should be set to the value 1.</p><p>　　C/A (Customer/Administrator): this field indicateswhether the user is a customer by writing “c” or an administrator by writing “a

78、”. This field has a size of 1 byte.</p><p>　　User ID: this field contains an ID for each user. The length of the field is 4 bytes.</p><p>　　Password: this field indicates whether the password be

79、longs to an administrator or a client. Administrators have full accessibility to change sensors status by using the set function, for example. The maximum length of this field will be 10 bytes which means the password ca

80、n't exceed 10 characters.</p><p>　　Station ID: this field contains the Station ID number. In this work, station IDs are assumed to be in the range of 1 to 9999. The length of this field is 4 bytes.</p

81、><p>　　Pointer ID: this field has the pointer ID number. The pointers' IDs will be in the range of 1 to 9999. The length of this field is 4 bytes.</p><p>　　The Query response frame: the respons

82、e frame will be sent from the Database to the administrator or client with the status of a specific sensor. A frame illustration is shown in Fig. 10.</p><p>　　The Station ID and Pointer ID have the same mean

83、ing as described above. The Value field contains the returned value of the item whose status is interrogated in the Query frame.</p><p>　　Note that the first 8 bytes in the response frame are used to store t

84、he following string: “The Query Results for PLC/Pointer Reading is”. Fig. 11 shows an SMS response to a query.</p><p>　　Fig. 11. A sample response.</p><p><b>　　中文譯文</b></p>&l

85、t;p>　　基于plc監(jiān)控應(yīng)用平臺的發(fā)展</p><p><b>　　文摘</b></p><p>　　本文論述了設(shè)計并實現(xiàn)了一個基于plc遠程監(jiān)視的平臺，控制過程由TCP / IP或使用GSM網(wǎng)絡(luò)控制。該平臺的建立是為了靈活的使用現(xiàn)成的plc。早期PLC結(jié)合處理器被用于對網(wǎng)絡(luò)的連接性和GSM調(diào)制解調(diào)器的聯(lián)系。通信處理模塊(以太網(wǎng)模塊)被用于這個工作,它提供了工

86、業(yè)兼容TCP / IP協(xié)議不可能達到的相同功能,但需要更高的帶寬(23百萬位元/秒)。此外,mobile-based通信協(xié)議讓我們的遠程監(jiān)視和控制plc在使用短信上也得到了發(fā)展。這里的意圖是給用戶提供一個通信機制的備份系統(tǒng),以防網(wǎng)絡(luò)失敗丟失數(shù)據(jù)。</p><p><b>　　1。介紹</b></p><p>　　最近的網(wǎng)絡(luò)技術(shù)發(fā)展特別是互聯(lián)網(wǎng)的廣泛傳播促進了分布式測量

87、系統(tǒng)在各種各樣的工業(yè)應(yīng)用。這些分布式測量系統(tǒng)都可以使用網(wǎng)絡(luò)[1,2]監(jiān)視和控制的各種機器。</p><p>　　一個可編程序控制器(PLC)microprocessorbased是可編程控制系統(tǒng),檢測,激活和控制工業(yè)設(shè)備,因此具有很多數(shù)量的輸入/輸出終端,連接到工業(yè)過程?？刂瞥绦蛴洃泝Υ嬖诳删幊绦蚩刂破?PLC)里它決定了PLC的投入與產(chǎn)出關(guān)系。 plc是智能自動化站它所擁有的非常有用和可取的功能,如[3]:&l

88、t;/p><p><b>　　?魯棒性。</b></p><p>　　?高度的可擴展性:家庭有一種現(xiàn)代可編程序控制器(PLC)寬頻譜的CPU類型,能輕松的擴展性功能和性能。</p><p>　　?可展開性:模塊化設(shè)計的plc可以與廣泛的數(shù)字和模擬的I / O模塊擴展。同時,各種集成技術(shù)模塊可用于各種各樣的應(yīng)用范圍。</p><p

89、>　　?復雜的溝通協(xié)調(diào)能力:現(xiàn)代plc能溝通各端口提供集中或分布式連接。</p><p>　　?強大的開發(fā)環(huán)境:現(xiàn)代的家庭用PLC通過環(huán)境的交叉來開發(fā),支持硬件配置、提供強有力的調(diào)試機制。</p><p>　　遠程訪問控制和監(jiān)控的各種各樣的設(shè)備工業(yè)設(shè)置是對工程師和自動化設(shè)備有價值的。</p><p>　　目前的實現(xiàn)的遠程PLC監(jiān)控是通過使用專用pc機或網(wǎng)絡(luò)服務(wù)

90、器連接到PLC的。圖1舉例說明了y用于工業(yè)的常見建筑式樣。如圖所示,plc通過電腦連接到網(wǎng)絡(luò)。PLC這種系統(tǒng)通常利用串行端口或Profibus介入這臺電腦。 這類系統(tǒng)的壞處在于只能使用計算機訪問PLC控制系統(tǒng)。建筑工作也沒有充分用到地區(qū)通信如電信和網(wǎng)絡(luò)技術(shù)。</p><p>　　圖一?；趐c的遠程可訪問性</p><p>　　近年來,由于日益擴大電腦計算能力和涌入的網(wǎng)絡(luò)協(xié)議和標準,已經(jīng)有

91、了更多的設(shè)計和實現(xiàn)分布式測量和控制系統(tǒng)為產(chǎn)業(yè)應(yīng)用。通常,這些系統(tǒng)的TCP /交流與溝通能力IP協(xié)議[4 - 6]是根據(jù)客戶的要求來建筑的?，F(xiàn)代plc來自嵌入式網(wǎng)絡(luò)為存取有用的實時信息和診斷提供服務(wù)器,可以通過任何一個標準的瀏覽器來查看。這個遠程的可訪問性提供的幾個的優(yōu)點是傳統(tǒng)的解決方案無法比擬的。例如,一個問題可以很容易通過遠程診斷修好;工程師也就可以通過固定的PLC的CPU遠程訪問,因此組態(tài)工具可以通過網(wǎng)絡(luò)或互聯(lián)網(wǎng)遠程上傳/下載配置工

92、具。</p><p>　　在本文中,我們將討論實現(xiàn)遠程plc控制控制網(wǎng)絡(luò)平臺的設(shè)計。圍繞plc西門子S7系列平臺。這些plc有一項可用于因特網(wǎng)聯(lián)合通訊處理器。在一個有線或無線環(huán)境實現(xiàn)監(jiān)視和控制,通過內(nèi)部網(wǎng)或互聯(lián)網(wǎng)為遠程監(jiān)控的工業(yè)加工提供完整的解決方案.我們還將討論利用GSM網(wǎng)絡(luò)和一個通訊協(xié)議運行用SMS消息與PLC電臺和數(shù)據(jù)庫服務(wù)器結(jié)合的系統(tǒng)。</p><p>　　摘要如下:組織描述了我們

93、在第二章整體的系統(tǒng)結(jié)構(gòu),第三部分包括討論一個軟件方面的系統(tǒng)。第四項、第五項部分呈現(xiàn)通信方法這個項目,論文的結(jié)論是第6部分。</p><p><b>　　2。系統(tǒng)結(jié)構(gòu)</b></p><p>　　在圖2舉例說明了該系統(tǒng)的體系結(jié)構(gòu)。該系統(tǒng)主要由以下組成部分:</p><p><b>　　圖2。系統(tǒng)架構(gòu)。</b></p&g

94、t;<p>　　?S7 200/300 PLC系統(tǒng)和溝通處理器(CPs)。每個CP有通信整合接口(硬件和軟件)使可編程序控制器(PLC)允許通過局域網(wǎng),廣域網(wǎng)或通過GSM網(wǎng)絡(luò)溝通。</p><p>　　?客戶和管理人員通過連接到工藝無線網(wǎng)絡(luò)(或有線網(wǎng))?？梢栽O(shè)定或重置管理員允許或限制的各種客戶的選擇的特權(quán)。</p><p>　　?數(shù)據(jù)庫服務(wù)器通過網(wǎng)絡(luò)連接到工藝為記錄數(shù)據(jù)日志和

95、事件。</p><p>　　?不同的網(wǎng)絡(luò)選擇包括GSM-based可訪問性。</p><p>　　PLC系統(tǒng)以太網(wǎng)模塊是一家以S7處理機連接可編程序控制器(PLC)的網(wǎng)絡(luò)。附加的溝通的方法是處理器的串行端口(RS232)與PLC和現(xiàn)代GSM之間的溝通。</p><p>　　提出的實施，PLC系統(tǒng)向遠程數(shù)據(jù)庫服務(wù)器傳遞地位。這數(shù)據(jù)庫服務(wù)器記錄了基于可編程控制器的plc

96、在桌面完成任何必需的數(shù)據(jù)分析狀況。系統(tǒng)也根據(jù)管理員控制受到并執(zhí)行廣大用戶的指令。GSM連通也執(zhí)行允許不同的特權(quán)地位的用戶強制性訪問的功能,讓他們可以控制編程序控制器(PLC)的這些功能。以太網(wǎng)和GSM連通的plc使用CP343實施和CP340處理器[7]溝通。</p><p>　　系統(tǒng)軟件實施主要使用Simatic Manager7和Java。Simatic Manager的環(huán)境使用PLC系統(tǒng)連接。該建筑允許規(guī)劃

97、、重組、設(shè)置該遠程系統(tǒng)。</p><p>　　Java應(yīng)用軟件利用S7-APIs(S7 -應(yīng)用編程接口)開發(fā)在數(shù)據(jù)庫服務(wù)器和PLC站點[8]建立通訊。例如,利用這些apis,我們可以根據(jù)包含在可編程序控制器(PLC)單位指定的IP的S7地址和中央處理器的地址連接數(shù)據(jù)庫服務(wù)器到PLC站點。</p><p>　　這可編程序控制器(PLC)使用I / O模塊連接到工藝傳感器與執(zhí)行器。</p

98、><p><b>　　圖3。系統(tǒng)軟件組件</b></p><p>　　使用S7-APIs應(yīng)用Java的后臺運行在服務(wù)器端創(chuàng)辦相關(guān)的可編程序控制器(PLC),它以Java數(shù)據(jù)庫中備案接頭技術(shù)(JDBC)儲存收回數(shù)據(jù)反映了各種可編程序控制器(PLC)數(shù)據(jù)表狀態(tài)參數(shù)。JDBC是一種允許Java連接數(shù)據(jù)庫服務(wù)器技術(shù)。它包含所需的Java圖書館里所有必要的連接數(shù)據(jù)庫服務(wù)器和執(zhí)行SQ

99、L語句。</p><p>　　整個系統(tǒng)允許用戶使用PLC設(shè)置過程值。 例如,用戶可以設(shè)置一個輸出(開動馬達)或</p><p>　　改變價值的一段記憶細胞(存儲器位,字節(jié)、文字、國旗,等)。制度環(huán)境也提供獲取輸入值的讀數(shù)(傳感器的閱讀資料)以及捕捉可編程序控制器(PLC)的狀況?？梢杂靡粋€圖表繪圖儀從plc來轉(zhuǎn)換成閱讀圖表。在完整的環(huán)境下一個錯誤報告機制給管理者提供有用的診斷信息。管理者系

100、統(tǒng)也可以通過GSM 網(wǎng)絡(luò)手機短信的形式查詢過程的狀況。最后,該系統(tǒng)建筑是可以圍繞著內(nèi)部網(wǎng)絡(luò)或互聯(lián)網(wǎng)完成plc網(wǎng)絡(luò)可擴展的監(jiān)控能力的。</p><p><b>　　3。系統(tǒng)軟件建筑學</b></p><p>　　該系統(tǒng)在此計畫中,使用的軟件分為三個部分:</p><p><b>　　?數(shù)據(jù)庫管理系統(tǒng)</b></p>

101、;<p>　　?應(yīng)用模塊(數(shù)據(jù)操作模塊、PLC的通信模塊,和GSM現(xiàn)代模塊)</p><p><b>　　?用戶界面上。</b></p><p>　　圖3描述了系統(tǒng)主要的軟件部件他們之間的交流的方向。描述每個部分的范圍內(nèi)以下。</p><p>　　3.1 一個整體的數(shù)據(jù)庫系統(tǒng)</p><p>　　使用Ora

102、cle9i數(shù)據(jù)庫被創(chuàng)立。它一個相關(guān)聯(lián)的表格的集合。圖四闡明了用于這項工作的數(shù)據(jù)庫模式。為了簡潔的描述每張表格下面被提供:</p><p>　　?一個配置表格,包含整個相關(guān)的信息如站和PLC IP地址、車站的名字,等。</p><p>　　?一個指針表,包含每個有關(guān)輸入,輸出或、記憶系統(tǒng)。指針代表輸入、輸出的地址,或者記憶。</p><p>　　?一個指針閱讀表用來存