Modula-2 based multitasking environment for a flexible biprocessor controller

Abstract

This paper presents the most important issues of a real-time software package developed for the industrial multiloop controller MMC-90. MMC-90 is a biprocessor system based on the concept of a two-level controller. On the lower level of complexity, the base control processor performs the basic control functions. On the higher level of complexity, the flexible control coprocessor executes complex functions on request from the control tasks on the base control processor. All the software on the control coprocessor is written in Modula-2. The corresponding multitasking environment was designed as a set of Modula-2 libraries at various horizontal and vertical decomposition levels. On the control coprocessor a preemptive, priority based scheduler as well as a high level interprocess communication and synchronization mechanism has been developed. Communication between the processors is realized by means of a fast bi-directional communication channel, which is implemented via dual-port RAM. The developed system opens the door to applications of modern control algorithms in industrial practice.