The data communication plays a very important role in fault diagnosis instrument system. In this paper, a flexible software bus method is proposed which is designed for the communication among instrument components. In this way, the data processing modules can be prefabricated together dynamically and in parallel. To carry out the communication between the bus and components, the design principle and the architecture of the components is discussed, and then the fault diagnosis instrument cases can be constructed by configuring the instrument components with the communication addresses. Based on the software bus, the processed data of fault diagnosis can propagate among the configured data flow ways asynchronously, and users can plug and unplug any components to the instrument platform. The application cases shows that the proposed way can accelerate data exchange among the modules based on the components and improve the working processes efficiency.