Abstract: A method for forming an actuating variable to be output periodically by a control unit in output periods for controlling an apparatus, in particular the ignition or fuel injection of internal combustion engines, includes reading output signals of at least two sensors into the control unit and ascertaining individual components of the actuating variable based on the output signals. The sensor output signals are read-in and the individual components are determined periodically at intervals of one read-in period or one determination period being equal to or a multiple of the output period of the actuating variable. The read-in period of a sensor output signal is dependent on a speed of variation of the sensor output signal, and in particular it increases as the maximum speed of variation of the sensor output signal decreases. The determination period of each individual component is dependent on the read-in periods of the sensor output signals involved in each individual component.