【作者】 张庆荣；

【导师】 余立建；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2002， 硕士

【摘要】 本硕士论文致力于研制一套分布式总体结构的基于RS-485总线和微机上实现的Modbus PLUS网络的天然气计量管理与远程监测系统。该系统定位于矿区与输配气站的应用，实现对各输配气站的数据采集、计量、管理及在管理中心的远程监测。所实现的系统具有实时性好、兼容性好、可扩展性强、抗干扰能力强、测量精度高、可靠性高，以及采用全中文人机界面等优点。 论文首先在需求分析的基础上进行了总体设计及现场子系统的物理结构设计，给出了系统的软件设计要求。分析了现场网络的形式，软件的设计与实现等。物理结构设计主要介绍了RS232、RS485、ADAM模块等的接口方式；软件设计主要介绍了程序中比较关键的通信模块和流量计量模块及数据库模块等，以及RS232，RS485，Modbus PLUS等接口的通信软件设计。重点讨论了现场子系统中的通信协议。其次，论文分别对现场系统的干扰问题及其提高可靠性措施进行了讨论，给出了管理中心和现场工控微机间的远程通信的实现方式。再次，论文给出了在VB开发环境下系统的实施，重点在通信设计，包括基于RS485总线的通信设计和Modbus通信协议在实际中的实现。最后对现在工业控制中的前沿技术——虚拟仪器技术进行了展望。更多还原

【Abstract】 This master thesis aims at developing a natural gas meterage, management and remote monitoring system with distributed hierarchy, which is based on the RS-485 bus and the Modbus Plus network in PC in the field. The system, which is oriented to the application to the stations of natural gas, is designed to meet data acquisition, meterage, management and remote monitoring in the supervising center. The system has the following remarkable features: real time response, high compatibility, high expandability, strong anti-interference, high precision, high reliability and friendly man-machine interface etc.Based on the requirement analysis, the overall design and the physical structure of the subsystem in the field are carried out firstly, and the design requirement of the software system is given. The paper analyses the network form in the field, and the design and implementation of the software. For software design, the communication module, flux measuring module, and database module are presented, and some communication interface such as RS232, RS485, Modbus is considered in the physical structure design. The emphasis is placed on the communication protocols of the subsystem in the field. Secondly, the thesis deals with the interference problem and the anti-interference techniques in the field subsystem. At the same time, the remote communication forms and implementation are presented between the subsystem and the supervising center. Thirdly, the detailed design and implementation of the system in the field in the visual basic integrated development environment are introduced. Here, attention is especially paid to the communication design, the communication design and implementation based on the RS-485 bus and the Modbus communication protocol. Finally, a conclusion is drawn from the paper and the technique of virtual instrument, the front technique in the field of industrial control, is mentioned.更多还原