Digital units are synthesized with different methods using formals as the final automata theory, or empiric, which are based on the experience of designer. In all cases implementing connection on specific industrial elements indetermination indications, which were existing at the drafting of the tasks theoretical part are turning into determination. In the function process of digital unit determinations are becoming into specific process, what sometimes can cause unexpected results hazard. Elimination of indeterminations are changed by passing from the specific solution back to automata behaviors defining, what is comparatively complicated, cause of few available appropriate programs. For the elimination of the listed mistakes, logical equipment on chosen elements can be checked with the Petri net simulation programs.