A system for producing a data stream based on redundant information that has a first controller, a second controller and a circuit. The first controller outputs a first part of first data via a first data output. The second controller outputs a second part of second data via a second data output. The circuit combines the data that is output to form a data stream. The first controller reads in at least the second part of second data of the combined data stream. The second controller reads in at least the first part of first data of the combined data stream. The read-in second part of second data is compared with a second part of the first data and if the comparison indicates a deviation, to stop outputting data via the first data output and/or to block the forwarding of the data stream.