A method for sensing input signal changes at an input of an input/output module operated in an automation system in which a signal is sampled by an input/output module. A change event and a timestamp associated with the change event are generated when a change in the sampled signal occurs and a value pair comprising the change event and the timestamp is stored in a higher-ranking automation component to the input/output module. The input/output module and the higher-ranking automation component are operated clock-synchronously with respect to one another by a clock pulse, and the timestamp is calculated centrally on the higher-ranking automation component based on the clock-synchronous operation.