Microcomputer-based multi-tasking on a SCADA system using interrupts in MS-DOS

Abstract This paper describes a multi-tasking operation using interrupts in MS-DOS for PC-based supervisory control and data acquisition (SCADA) systems. The structure of a generalized interface circuitry is formulated to serve as a standard interface for SCADA application programs to be independent from the types of hardware interface. Communication between processes is implemented through a set of common memory areas declared in one process. A prototype SCADA system employing five different types of hardware interface has been implemented through one main process for SCADA applications, a clock-based interrupted process to handle the scanning and the transformation of different types of hardware interface, and a serial port interrupted process for the communication to the RTUs and another PC.