This paper presents an architecture and design methods for rapid development of real-time control systems such as CNC or robot controllers. PICARD (Port-Interface Component Architecture for Real-time system Design) is a software architecture and environment which is aimed to reduce development time and cost of real-time control system. With PICARD, a control engineer can construct a control system software by assembling pre-built software components using interactive graphical development environment. PICARD has been used to implement a prototype PC based CNC controller successfully. PICARD consists of PVM (PICARD Virtual Machine), a component library, and PICE (PICARD Configuration Editor). PVM is a real-time engine of the PICARD system which runs control tasks on a real-time operating system. The component library is composed of components which are called task blocks. PICE is a visual editor which can configure control tasks by creating data-flow diagrams of task blocks or ladder diagrams for sequential logic. PICARD has been implemented on several operating system including QNX, WindowsNT (non-real-time), Linux (non-real-time), INtime, and RT-Linux. Compared to other operating systems, there are some differences on RT-Linux implementation in which real-time tasks should be written as kernel modules. For the communication between PVM on a target system and PICE on a host computer, a simple protocol was devised because RPC or CORBA cannot be used in RT-Linux. By using description of communication functions in Python language, function stubs are automatically generated. Experiences on using C++ language in kernel modules are also discussed.

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