The RTU Design Of Hydrologic Data Acquisition

China is a country prone to flood and drought. In order to reduce losses caused by flood and drought, the accurate forecast of water regime is of great significance. Hydrological information is the important basis for water regime forecast and policy-decision made by ministry of water resources. To automatically collect and deal with hydrological information, the hydrologic data acquisition system is constructed and RTU(remote terminal unit), an important component in the system, is responsible for colleting data sensor data and upload them to the central station and plays a pivotal role in transmission. Based on the above analysis on the extensive application of RTU in China, the author in the thesis concludes that the existing products meet with some problems such as high power consumption, poor stability and lower universality and so on, and thus, designs a new type of RTU.On the basis of the functional requirements of RTU, in the thesis, design principles and functions achieved by RTU are proposed, the overall analysis and design are conducted and the RTU hardware structure is designed and showed in detail. The design takes AT89S8252 microcontroller as the core and expands four serial ports for the need for data collection, communication and expansion. Besides, the thesis with modular methods designs data acquisition circuit, communication module and power management circuit, among which the data acquisition circuit is responsible for digital quantity, switch quantity, serial ports input and AD conversion; the communication module designs the FM radio module, extends the RS-485 interface and demonstrates the designed hardware circuit of the GPRS module; the power management module includes two parts : Regular power supply circuit and the controlled power supply circuit. Based on the constructed hardware circuits, the main program and the flow charts of important function modules are designed.The design features mainly lie on two aspects: power management and communication module. The former is used for achieving low power consumption and the latter regards the wide-geographical-coverage GPRS communication as the main ports and radio as the backup ports, and has a extended port for accommodating the specific circumstances, which great displays a design feature of universality. The features including low power consumption and universality make RTU fit for the automatic system of hydrological surveying and forecast.The thesis first gives a detailed introduction on the structure of the automatic system of hydrologic data acquisition system and RTU, discusses functional requirements of the system and the design principles and makes an overall design. Then the author focuses on the hardware circuit design and shows the software flow charts. Finally, the analysis and summaries are made and the prospect for this area is showed.