A Three Level Smart Long-distance Remote Monitoring System By Using PSTN To Construct Network

Long-distance distributed monitoring system have many ways, and the using modes of distance in tens kilometers or farther than this are very common. Typical monitoring systems are earthquake monitoring system, hydrographic monitoring system, oil monitoring system, autoreading system of water meter, watt-hour meter and gas meter in one and so on. At present, most of monitoring system is constituted by special transmitting systems such as fiber, radio net and special control computers. The author innovates and designs long-distance distributed three level monitoring system in the paper by using PSTN as channel according to require. At monitoring field RS-485 bus is used as the first level monitoring system because of multislaver and distance as far as 100m. The part is constituted by smart sensors and monitoring instrument. In order to dispose data at monitoring field; PC is adopted as local master, which constructs the second level monitoring system. Its function is data processing, and this data are useful for local relative departmentThe third level monitoring system is composed of communication unit, modem and PSTN. Central PC locates at monitoring center, linking all monitoring instruments by modem and gathering all data in central PC for further processing.The paper presents the design of the three level systems, and especially introduces realization of hardware and software of different parts in detail. Because of practicability of the system, relative department has accepted it. The author is preparing for industry trial and using in due form. The author programs, does experiments and draws the PCB. It is proved that the scheme is right and feasible, and can be used for reference for congener use.