A study on self-diagnosis of digital systems

The problem of automatic fault diagnosis of systems decomposed into a number of interconnected units is considered by using a simplified version of the diagnostic model introdu- ced by Preparata, Metze and Chien. The model considered in this paper is supp0sed to be a realistic representation of systems where each unit has a considerable computational capability. For any system of n units for which the set of testing links is given, necessary and sufficient conditions for t-diagnosability are presented in both cases of one-step diagnosis and diagnosis with repair. It is shown that, if the diagnostic model introdu- ced in this paper is applicable, the procedure for diagnosis with repair has very small complexity: this implies that diagno sis is possible with very little hard-core. The problem of optimal assignment of testing links in a system with n units in order to achieve a given diagnosability is also considered and classes of optimal t-diagnosable systems are presented for arbitrary values of t in both cases of one-step diagnosis and diagnosis with repair.