A system and method for changing safety-relevant data for a control device is provided wherein an authorized user inputs new or altered safety-relevant data, which is received on a data processing installation. A first checksum for the safety-relevant data is established and stored along with the safety-relevant data in at least one data record on the data processing installation. An enable code may also be stored in the at least one data record. This enable code may be produced by a code generator and encrypted by a key module. The data processing installation then reads back the safety-relevant data from a memory in the data processing installation, thereby allowing a comparison of the received safety-relevant data and the read back safety-relevant data. A second checksum is generated in a case where the comparison resulted in no differences. The second checksum may also be stored in the at least one data record. At least one new data record containing the safety-relevant data, the encrypted enable code and the first and second checksums is created and transmitted to the control device. The new data record is checked against prior data records and prior checksums stored on a storage medium to determine that the at least one new data record is known to the control device.