1. A method for ascertaining a load capacitance value of a data bus, the method comprising: reading in, via an interface of a control unit, a scaling factor of a synchronization pulse of the data bus; and determining the load capacitance value using the scaling factor and a processing rule; updating the scaling factor using a control loop; wherein an actual amplitude of a prior synchronization pulse is used as a control variable in the control loop, wherein a predetermined setpoint amplitude for the synchronization pulse is provided, wherein the control variable, which is the actual amplitude, is fed back via a negative feedback system, so that a control deviation, for updating the scaling factor, is determined as a difference between the setpoint amplitude and the actual amplitude, wherein the processing rule represents a relationship between the scaling factor and the load capacitance value, wherein the load capacitance value includes capacitances of clients on the data bus, and wherein the clients include sensors for an occupant protection system.