The Design Of Liquid Gas Network Monitoring System Based On ARM9

Liquid gas has been widely used in industrial production. To determine whether the remaining deficiencies or leaks for the storage of liquid gas, usually it is need to parameters such as the temperature in the storage tank and a liquid level measurement, But the liquid gas generally exists such as low temperature, toxic and other issues, and is generally stored in the tank group, which is inconvenient to measure the above parameters. How the liquid gas is insufficient margin automatic filling in order to maintain the stability of temperature and liquid level in the storage tank, and at the time of the accident alarm and emergency shutdown valve control, the liquid gas storage of intelligent monitoring and control is particularly important, related to instrument research and development has been the focus of scholars in our country and aboard. At present, the domestic and foreign related instruments usually use the old style button control, which function is simple and liquid crystal display and poor real-time response, poor equipment, poor network performance.According to the characteristics of the using of existing equipment, in order to increase the user’s experience, linkage control, measurement accuracy, reaction speed, this paper presents a based on ARM9 hardware platform running on WinCE environment of liquid gas temperature and liquid level equipment network measurement and control system design scheme, the sensor, feedback control and intelligent state display process, improve the environment of WinCE and liquid gas network monitoring system of automatic feedback control ability, solve between multiple devices network linkage communication conflicts and improve the accuracy of sensors to collect numerical. Using 7 inch LCD screen to change the user’s experience, the underlying data acquisition board data acquisition data and transfer data with LCD screen through the 232 interface. In this article,difficulties are mainly concentrated in the WinCE environment of the software algorithm to achieve efficient network feedback control, as well as to improve the accuracy of the shielding hardware difference algorithm.The contents of the paper are as follows:(1) For the problem of the single function of the feedback control system, the feedback control system is designed on the WinCE platform, and the feedback is automatically controlled by the assistant linkage. Automatic feedback control, the fuzzy feedback control algorithm based on improved and puts forward the multi interval fuzzy dynamic feedback algorithm, and this algorithm is used with multiple threads of tasks and timer software program, complete the preset interval of feedback control. Therefore, the control condition is no longer a single threshold, but the dynamic range of the user’s default. The system has been tested and verified by field test, the response rate is less than 0.1 seconds.(2) For the control of liquid gas tank group need, between multiple devices must be integrated communications and to solve the multi equipment linkage when communication collision problem, check on the table and grouping algorithm based on the proposed composite type communication under the environment of WinCE 485 bus equipment anti-collision algorithm. The standard output half duplex RS485 bus interface is used for the networking system, which can be read by the upper computer. The monitoring system of the liquid gas in the collision avoidance algorithm is verified by field test, and the reliability of the scheme is successfully applied to the linkage communication control of the 5 equipments.(3) The PT1000 resistance type temperature sensor, which is used in the process of measuring on the underlying data acquisition board,is varies with the extent of temperature and resistance by the op amp circuit transformation into a voltage signal, after A/D conversion by digital voltage value. Because of the difference of hardware, the voltage value is nonlinear with temperature, but the temperature difference can accurately cause the feedback control judging to be wrong. In order to get more accurate quantitative measurement of the temperature value on the curve fitting algorithm based on improved and the successive approximation curve fitting algorithm, through a plurality of temperature sampling points in the internal software of multi partition between the curve fitting of the calibration, temperature and voltage interval relation formula is obtained. Through these formula group obtains the digital voltage value a good match and the resistance of the sensor and the true temperature and can greatly eliminate caused by operational amplifier nonlinear characteristics and resistance accuracy error of measuring process measurement is a great error value, and ultimately to achieve the effect of shield the differences of hardware. Finally, the measurement results are stored in the WinCE database file and displayed in real time. The reliability and stability of the scheme are verified by field test, and the accuracy of the proposed algorithm is 1.5%.