A synchronisation process for an automation system (1) of redundant construction consisting of at least two partial systems (2, 2') which, to control a process, perform functionally identical sequences of machine commands (MP) which have incrementation instructions (IA) at mutually corresponding positions to increment a synchronisation counter (SZ, SZ'). Synchronisation takes place using the value of a synchronisation counter (SZ, SZ') at least when a partial system (2, 2') records a special event (11). To this end a synchronisation counter target (SZZ) is found so that the partial systems (2, 2') interrupt the execution of the sequence of machine commands (MP) at which the values of the synchronisation counter (SZ, SZ') reach the synchronisation counter target (SZZ).