OPC技术介绍(六)

本章介绍怎样利用微软的Visual Basic开发OPC自动化接口的客户应用程序。这里介绍的应用程序使用OPC数据访问自动化接口（版本2.0），进行同期方式和非同期方式的数据读取和写入。 ◆ 建立一个Visual Basic工程 利用Visual Basic开发OPC应用程序时，实现OPC自动化接口的OPC包装DLL是必须的。这个OPC包装DLL一般应该是由OPC服务器的供应商提供的。 启动Visual Basic 首先启动Visual Basic，新建一个Visual Basic的工程。请选择[标准 EXE]作为新建工程的类型（图1）。 图1 Visual Basic工程的建立 设置OPC包装DLL…     

OPC-XML服务器转换技术的研究及其实现

在深入分析COM和WEB服务的构件组成的基础上，利用VS．NET对现有OPC服务器进行转换，通过COM Inteerop连接低层的OPC服务器，访问现场数据；然后按照OPC XML规范具体实现OPC XML应具有的功能；最后按照SOAP和WSDL协议，实现OPC XML 服务器的WEB服务。完成对现有的基于OPCCOM接口规范的工业数据的XML化工作，很方便地实现了现存的基于COM技术的OPC服务器的升级，使得这两种接口可以和谐地共存。     

在.NET中激活基于COM的OPC数据存取定制接口

研究C#接口属性类后，编写了一个COM编排文件，将基于COM的OPC数据存取定制接口映射到．NET接口，有效地实现了遵循OPC数据存取规范2．0版本的代码从COM移植到.NET。文章的研究成果在工业自动化实时数据采集系统中具有实用价值。     

COM编排OPC数据存取规范3.0定制接口的研究

OPC数据存取规范基于COM，要将其移植到，NET平台，需要解决编排过程中数据类型转换、接口实现、参数传递等问题。研究C#接口属性类、.NET托管和非托管的转换后，解决了OPC数据存取规范3．0定制接口COM编排的问题。     

基于OPC数据访问标准客户端软件的开发

研究了OPC的基本结构和数据访问标准，重点分析了自动化接口的对象模型。使用Visual Basic编写了一个通用的OPC客户程序，采用了不同的数据访问方法，可以与众多OPC数据存取服务器进行数据交换。     

OPC技术介绍（四）

◆ OPC服务器对象 因为OPC服务器对象OPCServer提供连接数据源（OPC定值接口服务器）以及数据访问（读取/写入）的方法，所以在建立OPC组和OPC项以前必须建立OPC服务器对象，然后使用OPC数据访问自动化接口的“Connect”方法和数据源连接。本节说明一些经常使用的OPC服务器的属性和方法。本节的示例程序需要表1的示例基础。 表1 OPC服务器的示例基础 示例基础 Dim WithEvents AnOPCServer As OPCServer Set AnOPCServer = New OPCServer 属性：ServerState 说明 只读的属性，返回服务器的运行状态（OPCServerSt…     

基于OPC规范的客户应用程序实现

介绍了过程控制领域中引进的一种新技术—OPC数据访问标准，论述了OPC相关概念、基础及OPC标准接口，并以OPC数据访问定制接口规范(1．0A)为蓝本，给出了利用Visual C 实现OPC客户应用程序的详细步骤。     

OPC技术介绍(十三)

本章是介绍两种使用微软Excel的VBA(应用程序的Visual Basic)的OPC应用程序的开发方法。一种是直接使用OPC自动化接口的Excel应用程序的方法，而另一种是使用OPC ActiveX控件的Excel应用程序的开发方法。本章介绍的使用VBA的OPC应用程序的开发，是使用OPC数据访问(版本2.0)接口，进行同期方式的数据读取。有关怎样开发具有OPC读写功能的ActiveX控件，可以参考以前的内容。本章使用OPC ActiveX控件是由日本OPC协会开发的演示用软件组件。     

VC6.0编程客户端访问组态王OPC服务器的方法

介绍了OPC技术的体系结构原理和OPC客户端程序设计方法,提出了使用定制接口访问数据的OPC客户程序的方法,利用VC6.0编写了OPC客户端应用程序,详细介绍了OPC客户端应用程序实现的步骤。该方法使用组态王作为服务器,通过组态王的OPC接口来访问数据库中的数据变量,实现了OPC编程客户端与组态王服务器之间的数据交换。     

Delphi环境下使用定制接口开发OPC数据访问客户程序

简要的介绍了OPC以及使用定制接口开发OPC数据访问客户程序 的背景知识。文中较为详细的讲述了如何Delphi环境下使用定制接口开 发OPC数据访问客户程序。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

正~~