The Oil Tank Gauging System Based On Lonworks Technology--Software Design Of The DPU

In oil stock of the PLA the tank gauging duty is intensive and the measurement method is under-developed at present time. In order to resolve this problem and realize the automatic management, the POL Research Institute of General Logistics Department, PLA developed the automatic oil tank gauging system based on LonWorks technology and put it to use. The system runs reliably and stably and leads the tank gauging field in domestic. The author takes part in the research group and is responsible for the part titled "the software design of the Data Processing Unit".The automatic oil tank gauging system based on LonWorks technology consists of field devices on tanks, Data Processing Units, LonWorks fieldbus network and control computers. It can be used in the oil stock of army and petro-chemical industry. Data Processing Unit, the key device in the system, integrates the microcontroller and LonWorks technology and is a multi-channel, intelligent control device which can be used in the hazardous areas. Data Processing Unit, as a node of the LonWorks network, has the ability to process many types of signal and communicate with LonWorks network. The unit not only makes the data exchanging between the system and outside of it but also integrates the devices with different output signals or different communication protocols in one system.At the beginning of this thesis, the LonWorks fieldbus technology and its application in the oil tank gauging system are presented. The structure, function and characteristic with the principle and method of tank gauging system are described. Then the structure, principle of the circuit and the main chips of the Data Processing Unit are introduced. After this, the software design of Data Processing Unit including RS-485 (Modbus) module, 4-20mA analog module, on-off module, RTD module, pulse module, calculation and display module, communication module and neuron chip program module and also the method of resolving the problems which were found at the process of debugging are emphasized. Then the configuration software in monitor computer is briefly introduced. Finally, the author summarized some experience, noted some shortages and gave some proposal.