The dynamic features of systems in mathematical process simulation are often studied by looking at the response of the system to discontinuities in the input variables (Sprung-Antwort-Verhalten). A more detailed analysis ([2]) shows that for systems in the form of differential algebraic equations (even with index 1), which frequently occur e.g. in chemical engineering, a solution to the problem need not exist. In this paper we derive necessary and sufficient conditions for such systems to guarantee the solvability of the problem (Theorem 1). Further, a simple algorithm is stated (Theorem 3), which is suitable for numerical computation.