Design Of SCPI Parser Module On Instrument Interface Platform

With the rapid development of computer technology, the instrument industry has also experiencing a dramatic change, the manual operation of instrument change to automatic test by the computer. With the development of automated test technology and programmable instruments, We need the hardware interface standardization and the software control standardization.In hardware aspect, form the foundation of ATS concept in the fifties of the twentieth century, open standard interface bus was popularized in the eighties of the twentieth century after earlier specific interface and half-specific interface, the examples are RS232, GPIB, PXI and VXI.In software aspect, IEE488.2, printed in June, 1987, firstly solved the problem of data structure, but it still left designer the massive component semantics. The component data and the order of programmable instruments were not standardized until nine international instrument companies proposed SCPI on the basis of IEEE488.2 in April, 1990. SCPI aimed at reducing the program development time of ATS, protecting hardware and software investment of manufacturer and user, providing the widespread compatible coding environment for instrument control and data use.The instrument responds after it received SCPI: receive a string of news, analyze lexical, analyze syntax, generate intermediate code, generate and optimize target code. the syntax analysis module's performance directly affects the efficiency of the implementation of program-controlled. To further simplify the syntax analysis module in the instrument to improve the efficiency of the implementation of program-controlled, in this paper, we introduce a way of adding parser in interface circuit, which can change a complex character string of ASCII code into a simple character string of binary code. This way will greatly simplify the software work of the instrument designer, not only to achieve standardization of instrument language, but also improve the remote response rate, and would be useful when we design instruments by ourselves.There are many kinds of instrument interface, RS232 and GPIB are discussed in this paper. The instrument interface board is independent of the instrument, they have different microprocessor. In this way, the instrument design and the operation will not be affected, the interface board can also achieve versatility, the instrument can also achieve changeability. Firstly, I am absorbed in software design because of RS232 is simple, mainly consider how to change a complex character string of ASCII code into a simple character string of binary code. Secondly, I focus on hardware design by reasons of the main part of software design has completed and GPIB is a complex kind of interface, the main is the design of NAT9914 by CPLD, which is a GPIB interface chip. I also add the design of LCD to observe parser's result. The paper has made a useful attempt in developing the general and low price instrument interface board, the design makes some achievement for further ATS research.