A method for acquiring operating data of an internal combustion engine in a control unit during a diagnostic function of the control unit, and for transmitting the operating data from the control unit to a diagnostics device, the operating data being determined in the control unit with the aid of sensors assigned to the internal combustion engine. Desired operating data type and time resolution of the value reception is transmitted from the diagnostic device. Operating data are collected in the control unit with the aid of a diagnostic function. The diagnostics device and the control unit are connected via standardized interfaces, whose transmission speed is limited. Data values are buffered in a memory in the control unit. Speed of data acquisition may be selected independently of the transmission speed of the interface between the control unit and the diagnostics device. Data acquisition synchronous with the rotational speed is possible.