| Because of the rapid development of very large scale integration technology, the processing speed and computing ability of modern programmable logic device (PLC) have got very great improvement, thus it has changed enormously in the function on either software or hardware. In addition, the strong information processing function of PC, make more and more monitoring systems adopt PC-PLC structure. Though the uniform hardware structure has brought convenience for the system development, there is no design and development pattern suitable for software structure of monitoring system. So in this paper we analyze its existing problem in software based on PC-PLC structure, and propose the systematic framework, aiming to offer an overall solution for the monitoring system.In this paper, we launch research from two respects. First, the visualization of the monitoring system improves its function in the representation of scene. Second, a universal framework for this kind of system can be reused in most situations of system design and development.The simple animation using configuration software or static 2-D graphics is the commonest way to represent the state of the spot. But it cannot meet user's demands on displaying the scene. For this reason, we put forward a design philosophy of the Visualization Monitoring System (VMS), providing with a kind of new way for it to represent the on-the-spot state. Through summarizing and discussing the traditional 3-D graphics modeling and rendering, and also deeply analyzing the special requirements of the scene rendering for the monitoring system, we design a fast topographical model based on B-spline, a memory structure based on view points, and a tree-shape application data structure to set up scene model and navigate. We use OpenGL to realize the 3-D scene rendering. This visual monitoring system can get more natural human-computer interaction, express the on-the-spot scene and control the result dynamically. It provides users with the function of quick setting up and revising the scene model, and a good simulation results to many kinds of topography, such as platform, hills, slope, etc. At the same time the arithmetic of generating road can be used in different kinds of roads simulation.In this paper, we design the framework for the VMS on the basis of component-based software engineering, software framework, software reusing, interface tech-nology, XML technology and design pattern. The framework emphasis on two aspects, one is the INTERFACE and the other is BUS structure. Its conceptual model is a five-elements abstract model, representing the design method in five important aspects. It gives the common methodology in this field-software design for visualization monitoring system. The realization model of the framework provides the concrete structure in detail. Its key points are the mechanism of a pair of buses (control bus and data bus) and standardized interfaces. All the real applications depend on it. We use COM technology to realize the two most important function modules of the VMS framework (visual module and PLC communication and management module) and XML technology to realize data bus. This framework can be reused conveniently, expanded flexibly and have excellent stability. The developer can easily realize the new application or modify the old system according to the costumers' demands by making the new components or replacing the old one, which comply with the interface standard defined in this paper. And the structure of low-level coupling has guaranteed the stability of the software system.In summary, this visualization monitoring systems can improve traditional ones on displaying ability, the development efficiency, and software quality. VMS framework can be applied in illumination controlling system, fountain controlling system, scene monitoring system, etc.
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