Design And Implementation Of The Grating Signal Acquisition System Based On Ieee1284 Interface Standard Epp Mode

The grating displacement sensor is also called the metrology grating or grating ruler. As a kind of the displacement sensors, the optical signals are detected based on the effect of Moire fringe grating. The optical signals are converted to rectangular pulse signals by the optical-electric conversion and shaping circuits in the grating displacement sensor. It is mainly used to the measurements of linear displacement and angular displacement, such as the numerical control machine, lithography equipment, and high accuracy check of the displacement or the range in the field of mechanical industry. Therefore, the studies of the displacement detecting of the grating signal have highly practical values.We have designed a grating signal acquisition system based on CPLD and IEEE1284 parallel interface standard EPP model for the rectangular pulse signal, outputted by the grating displacement sensor. The software and hardware of this system had realized. The hardware of this system was composed of the grating signal processing circuit and the parallel interface communication circuit controlled by MCU. The design of grating signal processing circuits adopts modular design. CPLD and VHDL are used as the hardware and the program development language. The subdivision and direction-judgment module, the counter module, and the interface module are included in the grating signal processing circuits. The grating signal processing circuits are characterized by the high accuracy, wide measurement range and digital output. The data transmission to the host computer was realized by the parallel interface communication, controlled by MCU 8052. The computer parallel interface worked in the EPP model of IEEE1284 interface standard. The implementation was simple, convenient and safe. The software of the grating signal acquisition system includes the control programs on MCU, the driver programs on parallel port, and the computer application programs. The control programs on MCU are developed by C language, the driver programs on parallel port use Visual C++, and the computer application programs use Visual Basic. The grating signal acquisition system can measure the displacement correctly, has advantage of the characteristics of small volume, high precision, stable and reliable.