Abstract:This paper introduces the concept, application scenarios and implementation requirements of the programmable function in protection and monitoring device and proposes the design scheme of programmable function applicable to different hardware and software platform. Based on the analysis of data interface and definition between programmable function and standard or universal function, the design of programming language and the realization of compiling user programs to intermediate code and target code are elaborated. Finally, this paper demonstrates the method of executing user programs efficiently by constructing a logical stack in the virtual machine and proposes an approach of supporting software of graphical programming. The design scheme can provide flexible application programming interface for secondary development of protection and monitoring device.