Design of Portable Methane Concentration Alarm Monitor for Long Distance Control

摘要

The paper schemes out a portable methane concentration alarm monitor controlled by singlechip that detects the concentration of methane correctly. When the methane concentration in tested air exceeds the rated value, the monitor will give alarm and at same time make the exhaust unit function to remove the most hidden peril of safety production. The two main parts of the system unit are: hardware part and software part. The hardware part of the monitor consists of control processing unit (CPU) , small signal amplify circuit, A/D transform circuit, communication circuit, display circuit, watchdog voltage monitor circuit. Among these CPU is the core that performs the functions of data collection, processing, output, and display. Here AT89C51, a 8-bit CMOS microprocessor chip may be used for a wide variety of purposes such as highly currency, low-power consumption and excellent performance. Small signal amplify circuit adopted LM324 integrate ,which amplifies the voltage signal from sensitive component , A/D transmit circuit adopted TLC1543 chip from TEXAS instrument, which transforms analog signal to digital signal. Communication circuit used MSM7512B from OKI for its long distance, low-power consumption, high reliability, which sends information to long distance. Software part adopted blocking structure programming means, consisting of main procedure, timer interrupt service program, series port interrupt service program, sub-programs module, and so on. Initializtion is realized by main program module, turn on catalyse file, search status flags and control corresponding operating functions. The nature of the monitor is its long distance communication, the tested result can be sent for 20km away and the appearance of this instrument is beautiful to look at and delicate to carry convenient. The monitor can be used in small or middle-sized coal mine characterized for novel design of circuit, correct measurement parameters and convenient operation, etc.