Research And Design Of Communication Technology For Automatic Test Platform Of Oxygen Monitor

The airborne oxygen monitor is an airborne device that regulates and monitors the breathing supply of pilots. Its running state will affect the safety of pilots. Therefore, it is necessary to complete the functional test of the oxygen monitor periodically to ensure its reliability. The automatic test system designed for a certain type of oxygen monitor was used to test the accuracy and reliability of the oxygen monitor. The test process is fully automated. The test data can be displayed in real time, with the test report generated.The testing and debugging of the oxygen monitor are mainly dependent on the serial communication with the test equipment. The corresponding automated test system contains a number of sensors and instruments that require communication. In order to realize the communication of the electronic equipment, it can not only carry out the long-distance stand-alone communication, but also meet the requirements of the multi-node network communication in the automatic test system. A new type of interface scheme of single bus that is suitable for application environment was designed and improved in this dissertation.The single signal line master-slave structure was adopted in the communication interface scheme. The corresponding host interface circuit and slave interface circuit are designed at the same time. The slave interface circuit was designed with low power consumption, which belongs to the passive interface. It has the advantages of simple structure and low cost. The host interface circuit was designed by adopting the doubledrive and dual voltage, and the transmission circuit is driven by MOS tube and three state output. The analog digital conversion and the partial voltage receiving were adopted in the receiving circuit. In addition, the corresponding protection circuit was also provided.After modeling the transmission line, the whole communication network is simulated.The experimental results show that, the communication distance of the novel bus can reach 2km, the transmission rate is up to 38400bit/s, and the number of slave nodes is up to 450 under the condition of 5 twisted pair transmission medium.At last, a portable communication calibration module was designed by using the communication interface, and it is applied to the automatic test platform of oxygen monitor. Thus, the debugging method of oxygen monitor is extended. The interface described in this dissertation was adopted in the communication design of the oxygen monitor in the hardware. Based on the MSP430 MCU, the protocol program and the debugging program ware designed in the software. Finally, the PL2303 chip was used to achieve the MSP430 microcontroller serial port to the USB port conversion. The experimental results show that the oxygen monitor can be used in a stable and reliable real-time communication with the computer. After the realization of the module, theoxygen monitor can be detected by the oxygen monitor automatic test platform in real time, and it can be debugged automatically with the module.