Design And Implementation For Multi-channels Instrument Of PTCR Parameters Test

Testing the parameters of PTCR becomes more important for that PTCR devices are more widely used recently. The thesis discussed several common parameters testing theory and methods of PTCR based on PTCR testing principle and the national standards.In this thesis, the systematic architecture, hardware design, software design were mainly discussed.The hardware of the testing instrument consists of parallel port of computer and its enlarging circuit, recovery time testing circuit unit, data-acquisition circuit unit, protection circuit of overcurrent and the electro magnetic compatibility design of circuit diagram. 8255A chip was used to enlarge the parallel port circuit, so the hardware and expense of the system were reduced, and the anti-disturbing ability was enhanced. In the data-acquisition circuit unit, 12-bit A/D MAX186 was used to offer 1mV resolution ratio for test of resistance and 16-bit A/D MAX1302 was used to offer 1/16mV resolution ratio for test of current in balance-state.In order to increase the channels of the system in advance, the addresses of the decoding chips were optional. Every 8 channels was a group, and the total number of testing channels of the system could be expanded to 32.C++ was adopted as the programming language and Visual C++ was chosen as the developing platform. According to the testing process of PTCR, the software system offered convenient operation interface, accurate data-analyzing process and error-analyzing process. When the test was over, the instrument would be out of electricity automatically. The testing-data was analyzed and the plot would be displayed on the display.The testing program was executed to green setting-up applications with correlative dynamic link libraries and files by Setup Factory 7.0 software. The application could be run without Visual C++ installed on the personal compute and uninstalled conveniently.