ZigBee-Based Hydrological Telemetering System

Collection and transmission of data information like water level, rainfall and flow is a fundamental problem in water conservancy informatization. It provides the basis to correctly analyze and judge the situation of flood control and drought relief and to consequently draw up dispatching schemes.According to the needs of the Pearl River Water Resources Commission, considering hydrological telemetering characteristics and the Pearl River Basin hydrology environmental factors, this dissertation proposes a ZigBee-based wireless sensor network which is low cost, low energy consumption and easy monitoring, and discusses in detail the system's overall structure and basic principle. According to the solution, the RTU (Remote Terminal Unit), hydrological equipment acquisition and control unit, and central station PC software has been developed.The communication network scheme is a combination of ZigBee and GPRS network protocol. The remote nodes in Hydrological telemetry system communicate with RTU by RS-485 or ZigBee, and RTU communicates with PC of the central station through GPRS network. The working mechanism used in the system is a combination of self-reported mode and response mode. The main features of the work system include simple in structure, low power, and easy maintenance.In order to realize low power consumption, multi-sensor, high stability which is required by Hydrological telemetry system, RTU uses LP3500 as a core chip, and its main functions include human-computer interaction, storage, timing check, GPRS communications and others. CC2430 is used as the core chip for hydrological equipment acquisition and control unit in order to meet the needs of ZigBee networking, and its main function is to control, operate, read data from hydrological instruments, and then convert the data to standard MODBUS protocol so as to communicate with RTU. The remote stations are powered by storage batteries and solar floating charge. The capacity of storage batteries and solar cell is determined by the voltage, allowed range of voltage fluctuation, equipment power consumption and the average annual sunshine intensity, as well as the number of consecutive rainy days in each station site.Embedded software development primarily uses C language. Since the RTU module chooses the Rabbit(?) microprocessor as its core chip, Dynamic C development environment and collaborative multi-task operating system are used. Software development of acquisition uses IAR Embedded Workbench IDE development environment, embedded with ZigBee networking mechanism which is based on streamlined stack to complete the remote node networking function.PC software development uses Delphi development environment, the language of which is a set of object-oriented extensions to standard Pascal. Key features include data collection, storage, RTU configuration, information acquisition and so on.Currently, the system has completed a six-month laboratory test conducted by Zhengzhou Yellow River Conservancy Committee. The system has been fully installed in the Pearl River Hydrological Station and it is in trial operation now.