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In order to improve accuracy of measuring motor speed in precision motor control systems, a method of precise measurement of speed with CPLD is proposed, which measures the truncated parts of the measured pulse on the basis of measuring raster count pulse within the equal period, and takes them as compensation, thus improving accuracy of measuring the raster pulse. In this paper, a speed measuring formula is given. Measuring system is provided with parallel and serial communication interfaces for output of measurement results.

This paper discusses disadvantages of existing diagnosis fault system for reciprocating machinery, and based on structural characteristics and operating principle of the reciprocating machinery, it also presents that a portable fault diagnosis system of reciprocating machinery shall be composed of three parts: sensor, data acquisition device and hand-held terminal, in which the data recorder is mainly prSovided for signal conditioning, A/D for data conversion and transmission, and hand-held terminal for data receiving and processing, fault diagnosis, display and storage. The experiment and tests show that this portable fault diagnosis system is feasible for field online monitoring of status and fault diagnosis for reciprocating machinery.