Safety controller and safety control method

Abstract

The present invention relates to time partitioning to enable execution of tasks in a constant cycle while guaranteeing dependence of a safety-related system. A safety controller includes a processor and a system program for controlling allocation of an execution time of the processor to tasks. The processor executes the system program to schedule tasks in accordance with scheduling information indicating, in a constant cycle, a period of one of a safety-related TP to which a safety-related task belongs and a non-safety-related TP to which a non-safety-related task belongs. In a task of a TP in the constant cycle, the processor stores the end information upon completion of processing in the task and brings the task into a ready state. In the scheduling, when the end information is stored, the processor inhibits allocation of the execution time even when the task in the TP in the constant cycle is in the ready state, and deletes the end information during a period between an end of the period of the TP in the constant cycle and a start of a period in a next cycle of the TP.