A DAISY ARCHITECTURE FOR THE MULTIPROCESSOR REAL-TIME DATA ACQUISITION-SYSTEM OF THE THOR TOKAMAK EXPERIMENT

The real time data acquisition system designed and built for the Thor Tokamak experiment is presented. The characteristics of present-day magnetic confinement fusion experiments impose a set of design constraints which can be met only through a careful analysis of the architectural model to be adopted. The Daisy architecture used here is mainly characterized by centralization of control and modularity. Its properties are analyzed and shown to be capable of satisfying the experiment requirements. According to this choice, the hardware system consists of several microcomputers which are controlled by a central minicomputer through the exchange of messages. The software system structure directly reflects the hardware organization. The solutions adopted for data acquisition, storing, processing and displaying and for error handling are also described. Parallel activation of different functions of the system is used to improve speed and is achieved through the multiprocessor and multiprogramming facilities.