A method and a device for monitoring data and the transmission of data between at least one first control unit and one second control unit are provided. The at least two control units have a first program level, to which are allocated programs which calculate the control function, as well as a second program level including programs that monitor the functional reliability of the programs of the first program level. The first control unit is connected to at least one component which may be used to acquire data, for example, controlled variables. The data acquired by the component or further data determined with this data may be transmitted from the first control unit to the second control unit over a single connection in a secure manner, and the data and the data transmission are secured separately in the first and second program levels such that errors in the data and the data transmission may be detected.