Based On Lonworks Technology Combustible Gas Sensor Research And Development

The research and development of the fieldbus-based inflammable gases sensor aim at applying LonWorks technology to the conventional gases detection, providing the sensor with the functions of the fieldbus instrument, constituting the inflammable gases detecting network. Up to now, it is unusual to develop the inflammable gases detecting system based on fieldbus. Therefore, the research is of importance both in theory and practice. In the developing of the inflammable gases sensor based on LonWorks technology, the main researches of this thesis are as follows:1. The total scheme of the inflammable gases sensor is designed, and the sensor has the functions of the fieldbus instrument.2. Various kinds of the inflammable gases sensitive element made in both overseas and inland are compared in price and performance. Then the catalytic contact combustion sensing element is selected due to its high performance and low cost.3. The MAX1400 ADC developed recently by MAXIM is adopted in signal conditioning circuit, because of its high quality, new technology and integrated functions, including the sampling, amplifying, filtering and A/D conversion all in together. Hence the circuit has the following advantages, such as the hardware simplification, high accuracy of the signal processing and perfected performance.4. After analyzing and mastering the LonWorks technology, we have developed the prototype of the inflammable gases sensor by means of the reasonable design of hardware and software. The Neuron chip is the kernel of the prototype. It is proved that this sensor achieves the predetermined performance by the experiments.The techniques and methods developed in this thesis could also be used in the development of other fieldbus sensor or instrument, such as the instruments of temperature, pressure, flow rate and liquid level etc.