文獻(xiàn)翻譯-可視化的plc程序使用xml

1、<p>　　附錄一：外文文獻(xiàn)原文</p><p>　　Visualization of PLC Programs using XML</p><p>　　M. Bani Younis and G. Frey</p><p>　　Juniorprofessorship Agentenbased Automation</p><p>　

2、　University of Kaiserslautem</p><p>　　Abstract - Due to the growing complexity of PLC programs there is an increasing interest in the application of formal methods in this area. Formal methods allow rigid pr

3、oving of system properties in verification and validation. One way to apply formal methods is to utilize a formal design approach in PLC programming. However, for existing software that has to be optimized, changed, or p

4、orted to new systems .There is the need for an approach that can start from a given PLC program. Therefore, for</p><p>　　I. INTRODUCTION</p><p>　　Programmable Logic Controllers (PLCs) are a spec

5、ial type of computers that are used in industrial and safety critical applications. The purpose of a PLC is to control a particular process, or a collection of processes, by producing electrical control signals in respon

6、se to electrical process- related inputs signals. The systems controlled by PLCs vary tremendously, with applications in manufacturing, chemical process control, machining, transportation, power distribution, and many ot

7、her fields. </p><p>　　With the widening of their application horizon， PLC programs are being subject to increased complexity and high quality demands especially for safety-critical applications. The growing

8、complexity of the applications within the compliance of limited development time as well as the reusability of existing software or PLC modules requires a formal approach to be developed [I]. Ensuring the high quality de

9、mands requires verification and validation procedures as well as analysis and simulation of exi</p><p>　　Visualization of existing PLC programs is an important intermediate step of Reverse Engineering. The p

10、aper provides an approach towards the visualization of PLC programs using XML which is an important approach for the orientation and better understanding for engineers working with PLC programs. </p><p>　　Th

11、e paper is structured as follows. First, a short introduction to PLCs and the corresponding programming techniques according to the IEC 61131-3 standard is given. In Section Ⅲ an approach for Re-engineering based on form

12、alization of PLC programs is introduced. The transformation of the PLC code into a vendor independent format is identified as an important first step in this process. XML and corresponding technologies such as XSL and XS

13、LT that can be used in this transformation are presented i</p><p>　?、?PLC AND IEC 61131</p><p>　　Since its inception in the early ‘70s the PLC received increasing attention due to its success in

14、 fulfilling the objective of replacing hard-wired control equipments at machines. Eventually it grew up as a distinct field of application, research and development, mainly for Control Engineering. </p><p>　

15、　IEC 61 131 is the first real endeavour to standardize PLC programming languages for industrial automation. In I993 the International Electrotechnical Commission [4] published the IEC 61131 Intemational Standard for Prog

16、rammable Controllers. Before the standardization PLC programming languages were being developed as proprietary programming languages usable to PLCs of a special vendor. But in order to enhance compatibility, openness and

17、 interoperability among different products as well as to prom</p><p>　　Instruction List (IL) is a low-level textual language with a structure similar to assembler. Originated in Europe IL is considered to be

18、 the PLC language in which all other IEC61 131-3 languages can be translated.</p><p>　　Ladder Diagram (LO) is a graphical language that has its roots in the USA. LDs conform to a programming style borrowed f

19、rom electronic and electrical circuits for implementing control logics.</p><p>　　Structured Text (STJ is a very powerful high-level language. ST borrows its syntax from Pascal, augmenting it with some featur

20、es from Ada. ST contains all the essential elements of a modem programming language.</p><p>　　Function Block Diagram (FBD) is a graphical language and it is very common to the process industry. In this langu

21、age controllers are modelled as signal and data flows through function blocks. FBD transforms textual programming into connecting function blocks and thus improves modularity and software reuse.</p><p>　　Seq

22、uential Function Chart (SFC) is a graphical language. SFC elements are defined for structuring the organization of programmable controller programs.</p><p>　　One problem with IEC 61 131-3 is that there is no

23、 standardized format for the project information in a PLC programming tool. At the moment there are only vendor specific formats. This is also one reason for the restriction of formalization approaches to single programs

24、 or algorithms. However, recently the PLC users’ organization PLCopen (see http://www.plcopen.org) started a Technical Committee to define an XML based format for projects according to IEC 61131-3. This new format will e

25、ase the acc</p><p>　?、? RE-ENGINEERING APPROACH</p><p>　　The presented approach towards re-engineering (cf. Fig.1) is based upon the conception that XML can be used as a medium in which PLC code

26、s will be transformed.</p><p>　　This transformation offers the advantage of obtaining avendor independent specification code. (Even if the PLCopen succeeds in defining a standardized format for PLC applicati

27、ons, there will remain a lot of existing programs that do not conform to this standard.) </p><p>　　Based on this code a step-wise transformation to a formal model (automata) is planned. This model can then b

28、e used for analysis, simulation, formal verification and validation, and finally for the re-implementation of the optimized algorithm on the same or another PLC.</p><p>　　Since re-engineering of complete pro

29、grams will, in most cases, be only a semi-automatic process, intermediate visualization of the code is an important point. At different stages of the process different aspects of the code and/or formal model have to be v

30、isualized in a way that a designer can guide the further work. XML with its powerful visualization and transformation tools is an ideal tool for solving this task.</p><p>　　IV. XML AS A TOOL FOR VISUALIZATIO

31、N</p><p>　　XML (extensible Markup Language) is a simple and flexible meta-language, i.e， a language for describing other languages. Tailored by the World Wide Web Consortium (W3C) as a dialect of SGML [S], X

32、ML removes two constraints which were holding back Web developments [6]. The dependence on a single, inflexible document type (HTML) which was being much abused for tasks it was never designed for on one side; and the co

33、mplexity of full SGML, whose syntax allows many powerful but hard-to-program options</p><p>　　While HTML describes how data should be presented, XML describes the data itself. A number of industries and scie

34、ntific disciplines-medical records and newspaper publishing among them-are already using XML to exchange information across platforms and applications. XML can be tailored to describe virtually any kind of information in

35、 a form that the recipient of the information can use in a variety of ways. It is specifically designed to support information exchange between systems that use fundam</p><p>　　Using XML with its powerful pa

36、rsers and inherent robustness in terms of syntactic and semantic grammar is more advantageous than the conventional method of using a lexical analyzer and a validating parser (cf. Fig. 2, [7]).</p><p>　　The

37、conventional method of analysis of program code requires a scanner (lexical analyser) which generates a set of terminal symbols (tokens) followed by a parser that</p><p>　　checks the grammatical structure of

38、 the code and generates an object net. In the object net the internal structure of the program is represented by identified objects and the relations between them. Both the scanner and the parser to be used in this metho

39、d are document oriented which implies that analysis of different types of documents requires rewriting the generated code for the scanner and the parser. An example of an application of this method can be found in [8].&l

40、t;/p><p>　　The most promising aspect of using XML instead is that XML and its complementary applications for transformations are standardized so as to provide maximum flexibility to its user.</p><p&g

41、t;　　The XML based method is advantageous, since the lexical specification is an invariant component of XML; therefore the well-formedness is independent from the respective individual application.</p><p>　　H

42、ence, an XML-Parser also can transfer well-shaped XML documents in an abstract representation called Document Object Model (DOM) without using a grammar. DOM is an application programming interface (APII) for valid HTML

43、and well-formed XML documents. It defines the logical structure of documents and the way a document is accessed and manipulated. In the DOM specification, the term "document" is used in a broad sense increasing

44、ly. XML is used as a way of representing many different kind of infor</p><p>　　XSLT, the transformation language for XML is capable of transforming XML not only to another XML or HTML but to many other user-

45、friendly formats. Before the advent of XSLT, the transformation of XML to any other format was only possible through custom applications developed in a procedural language such as C++, Visual Basic or, Java. This procedu

46、re lacked the generality with respect to the structural variation of XML documents. Capitalizing on the concept that the custom applications for the tra</p><p>　　XSLT functions in two steps. In the first ste

47、p, it performs a structural transformation so as to convert the XML into a structure that reflects the desired output. The second stage is formatting the new structure into the required format, such as HTML or PDF (cf. F

48、ig. 3 ). The most important advantage of this transformation is that it allows a simple and easily-conceivable representation of the document or data structure embedded inside the well-structured but hard-to-understand X

49、ML to be produc</p><p>　　Every XML document has its own syntax and vocabulary. Therefore, in addition to being well-formed, the XML document needs to conform to a set of rules. According to W3C recommendatio

50、ns this set of rules has to be defined either through a Document Type Definition (DTD) or an XML Schema. The rules defined in a DTD or an XML Schema state the hierarchical and structural constraints of the XML document.&

51、lt;/p><p>　　The DTD is for defining the document grammars; more recently a number of alternative languages have been proposed. The W3C XML Schema language replicates the essential functionality of DTDs, and add

52、s a number of features: the use of XML instance syntax rather than an ad hoc notation, clear relationships between schemas and namespaces, a systematic distinction between element types and data types, and a single-inher

53、itance form of type derivation. In other words schemas offer a richer and more pow</p><p>　　V. AN APPROACH FOR THE VISUALIZATION OFPLC PROGRAMS</p><p>　　A. Overview</p><p>　　Since I

54、nstruction List (IL) is the most commonly used PLC language in Europe, the presented approach is based on this language. The proprietary IL dialect Siemens STEP 5 and the standardized version according to IEC 61131-3 are

55、 considered.</p><p>　　The generation of XML documents showing different aspects of a PLC program is realized in the following three steps (cf. Fig. 5):</p><p>　　1.Transformation of the PLC progr

56、am to an XML document</p><p>　　2.Validation of the XML against the XML Schema which sets the syntax of the XML</p><p>　　3.Identification of the Instruction elements of the transformed XML accord

57、ing to the instruction set of the source PLC</p><p>　　These three steps are discussed in sub-sections B to D respectively. Sub-section E explains the visualization of the different XMLs obtained during the p

58、receding steps.</p><p>　　Throughout this Section an example is used to illustrate the presented concepts. Fig. 6 shows a PLC code written in Instruction List Siemens S5. The PLC code is written in atabular f

59、orm where each row element is either a delimited list consisting of address, label, instruction, operand and description or a comment.</p><p>　　Kommentar :</p><p><b>　　Autor</b></

60、p><p>　　Erstellt :15.07.2003 Geaendert am: B1B:O</p><p>　　NETZWERK 1 EMPFANGEN SLAVE 3 VON MASTER</p><p>　　NAME :EMPE'MAST</p><p>　　0005 :U M98.7 ABFRAGE OB EMPFANG MO

61、EGLICH</p><p><b>　　0006</b></p><p>　　0007 :SPB= MOOl</p><p><b>　　0008</b></p><p>　　0009 :A DB140 EMPFANGSFACH IST DB 140</p><p>　　O

62、OOA :L KF+20 LAENGE DES DATENPAKETS</p><p>　　oooc :T DLO</p><p>　　OOOD :L KF+O ZIELNUMMER O=MASTER</p><p>　　OOOF :T DRO</p><p><b>　　0010</b></p><

63、p>　　0011 :UNM98.7 FANGEN WIEDER ERLAUBEN</p><p>　　0012 :S M98.7</p><p>　　0013 MOOl :NOP 0</p><p><b>　　0014</b></p><p>　　0015 :BE BAUSTEIN ENDE</p>

64、<p>　　Fig. 6 A PLC program written in Siemens S5 Instruction List</p><p>　　B. Conversion of a PLC Program inio a well-formed XML</p><p>　　Given a PLC program in ASCII format and in a tabul

65、ar structure with separate columns for addresses, labels, instructions, operands and descriptions delimited by whitespaces, XSLT can convert it into a well-formed XML document. The XML document obtained through this tran

66、sformation is a hierarchically structured document.</p><p>　　Fig. 7 shows the XML document obtained through the transformation of the PLC code of Fig. 6. The XML document is structured in a hierarchy in whic

67、h the root element is the IL Code Block representing the whole PLC code. Each of the rows of the PLC code is contained within a corresponding ILRow element which is M e r smtctured into child elements.</p><p&g

68、t;　　Note: The structure chosen for the XML representation of IL-Code is oriented at the working proposal of the PLCopen.</p><p>　　C. XML Validation against the XML Schema</p><p>　　The XML obtain

69、ed as a result of the previous processing can be validated using a validating parser that confirms that the XML document in addition to being well-formed conforms to the set of syntactic rules defined in context of the P

70、LC programming language.</p><p>　　D. rdenhpcation of instructions</p><p>　　This step in the process of visualization of PLC programs using XML ensures that the XML document to be used for visual

71、ization contains only valid instructions.XSLT can be used to transform the well-formed and valid Xh4L to another XML which as a result of identification on instructions has an additional attribute appended to the instruc

72、tion tags. This attribute notifies whether the instruction is a valid instruction of the concerned instruction set. This transformation procedure is also capable</p><p>　　The instruction identification of th

73、e transformed XML proofs the semantic of the XML in accordance with the operation types of the PLC programming language.</p><p>　　In the example of this section, (cf. Fig. 8), the new XML contains additional

74、 attributes which classify the instructions according to the type of operation it represents. The STEPS instructions are categorized into eleven different types of operations e.g. logical, jump, load or transfer operatio

75、n assignment, etc.</p><p>　　<?xml version="l.O" encOding="ISO-8859-1" ?></p><p>　　<ILCodeBlock></p><p><b>　　<ILRow></b></p>

76、<p>　　(Instruction instructionId='Logical Operation")</p><p>　　U</Instruction></p><p><b>　　</ILROW></b></p><p><b>　　-.</b></p>

77、;<p><b>　　<ILRow></b></p><p>　　<Instruction instructionId="Jump Operation"></p><p>　　SPB-</Instruction></p><p>　　<Instruction instr

78、uctionId=" special Operation</p><p>　　"> BE</Instruction></p><p><b>　　</ILROW></b></p><p><b>　　</ILRow></b></p><p&g

79、t;　　Fig. 8 A new transformed XML showing only the inslructions and the</p><p>　　corresponding instruction ID</p><p>　　</ILCodeBlack></p><p>　　E. Visualization of XML</p>

80、<p>　　Both of the XML documents generated above can be transformed into HTML or other readable documents with the help of XSL. An ingenious XSL can be designed so as to produce an HTML which can convey the logical

81、 and other features of the PLC program in an easily conceivable form. Moreover, the DOM structure embedded in the XML (cf. Fig. 9), also enables the user to navigate through the PLC programs in an easy way.</p>&l

82、t;p>　　For the example the visualization is done in HTML. This visualization is done for the transformed XML after the validation of it's syntax as a table where the child elements of the ILRow are the columns of t

83、his table.</p><p>　　The XML after the instruction identification is transformed using the XSL, where the instruction and the instruction Id, obtained after extracting the XML according to the type of operati

84、ons are visualized in a table containing two columns (Instruction, Instruction Id) in HTML.</p><p>　　The HTML structures suggested here are not the only possibilities, with which the XML can be visualized, b

85、ut they give a very easy practical option for the user's grasp of the PLC code. Fig. IO shows the same PLC code as shown in Fig. 4 as a HTML document converted &om the XML document shown in Fig. 7 using XSL. This

86、 visualization enables a better understanding of the PLC program. Fig. 11 shows the special visualization of instruction ids given in the XML of Fig. 6.</p><p>　　VI. CONCLUSIONS AND OUTLOOK</p><p&

87、gt;　　Re-engineering of PLC programs needs a formal approach to be developed. In this paper one way to solve this task is introduced. Based on a given PLC program written in Instruction List a step-wise transformation to

88、a formal representation is proposed. Since this process will not be fully automatic, the need for flexible visualization of intermediate steps is derived. XML is presented as a flexible, standardized means to serve as da

89、ta format for the description of the PLC code. The corresponding </p><p>　　Based on the XML description of PLC programs further transformations will be applied to finally derive a completely formalized descr

90、iption of the original PLC code. This will be in the form of a finite automaton. During this process it is planned to identify common IL structures and formalize them via a library.</p><p>　　Gaining the Bene

91、fit of the XML Metadata Interchange (XMI) as an open industry standard that applies XML to abstract systems such as UML and referring to the classification of the instructions of IL into the eleven categories mentioned a

92、bove. We can extract UML classes from this classification, as it resembles the action semantics of UML.</p><p>　　VII. AKNOWLDGMENT</p><p>　　We would like to express gratitude to the “StiAung Rhe

93、inland-Pfalz fir Innovation” for sponsoring our work under project number 616.</p><p>　　VIII. REFERENCES</p><p>　　1. L. Baresi, M. Mauri, A. Monti, and M. Pezze, “PLCTools: Design, Formal Valid

94、ation, and Code Generation for Programmable Controllers”, in. IEEE</p><p>　　Conference on Systems, Man, and Cybernefics (SMCZOOO), Nashville, USA, Oct. 2000, pp. 2437- 2442.</p><p>　　2. G. Frey

95、and L. Litz, “Formal methods in PLC programming”, in IEEE Con on Systems, Man and Cybernetics (SMC’ZOOO), Nashville, USA, Oct. 2000, pp.</p><p>　　2431-2436.</p><p>　　3. M. Bani Younis and G. Fre

96、y, “Formalization of Existing PLC Programs: A Survey.“, in CESA 2003, Lille (France), Paper No. S2-R-00-0239, July 2003.</p><p>　　4. International Electrotechnical Commission, IEC International Standard 1131

97、-3, Programmable Controllers, Part 3, Programming Languages, 1993.</p><p>　　5. World Wide Web Consortium: htfp;//www.w3.org/</p><p>　　6. XML Home Page: hftp://xml.com/</p><p>　　7.

98、R. Kliewer, Reverse Engineering von Steuerungssojiware.Ph.D. thesis, University of Kaiserslautern, Germany,Institute for Production-Automation, 1999.</p><p>　　8. M. Kay, XSLT - Programmer’s Reference. ISBN18

99、61005067, Wrox Press Ltd2001</p><p><b>　　附錄二: 翻譯</b></p><p>　　可視化的PLC程序使用XML</p><p>　　M. Bani Younis and G. Frey</p><p>　　摘要:由于P LC程序日益復(fù)雜,在PLC應(yīng)用方面有越來越多的興趣愛好

100、者。形式化方法，讓僵化的證明系統(tǒng)屬性被核查和驗(yàn)證。一個(gè)傳統(tǒng)思路的方法就是在PLC編程中設(shè)立一個(gè)正式的設(shè)計(jì)方法。不過，現(xiàn)有的軟件已被優(yōu)化，改變，或移植到新系統(tǒng).有需要找到從某一PLC程序開始的方法。因此，規(guī)范PLC程序是一個(gè)現(xiàn)在研究的熱點(diǎn)。該文章概述了基于形式化的PLC程序基礎(chǔ)上從新啟動(dòng)的方法。轉(zhuǎn)型成為一個(gè)獨(dú)立的格式和可視化的結(jié)構(gòu)，在這個(gè)過程中，PLC程序的確定是作為這項(xiàng)措施的重要中間步驟。這表明如何XML和相應(yīng)的技術(shù)可用于形式化和可視化

101、現(xiàn)有的PLC程序。</p><p><b>　　1、導(dǎo)言 </b></p><p>　　可編程邏輯控制器（PLC ）是一種特殊類型的計(jì)算機(jī)，它應(yīng)用于工業(yè)和安全的關(guān)鍵地方。應(yīng)用PLC的目的是控制某一特定的或可選擇的過程，它是通過產(chǎn)生的電控制信號(hào)回應(yīng)電器中相關(guān)的輸出信號(hào)來實(shí)現(xiàn)的。應(yīng)用在制造業(yè)和化工過程控制，機(jī)械加工，交通，電力分配，以及其他許多領(lǐng)域。PLC控制有著極大的不