Abstract <p>The results of a reliability study of digital management software for multiloop objects, information processes, and systems are presented. Mathematical models of the control object, control program, and processes of the occurrence of malfunctions and failures under digital control are developed. Expressions for calculating the estimates of software development time to malfunction and to failure are obtained. Poisson flows of malfunctions and failures of software and a digital control system in general are described. It is shown that the synthesized mathematical models enable correct prediction of software failures in digital control systems.</p>