Unidirectional data transfer system and corresponding method

A system (3) for unidirectional data transfer comprising a data emitting device (5), a data receiving device (6) and a first unidirectional wire link (7) connecting the emitting and receiving devices such that the data passes from the emitting device to the receiving device, the first wire link including a non-controllable unidirectional component (8), the unidirectional transfer system further including a device (19a, 19b, 20) for monitoring the quality of the transferred data, characterised in that the device (19a, 19b, 20) for monitoring the quality of the transferred data includes, in each of the emitting (5) and receiving (6) devices, a module (19a, 19b) for calculating an error check code comprising the same algorithm (ALGO1) for calculating the check code, means (COMP) for comparing check codes incorporated into the emitting device configured to compare a check code received via the first wire link (7) and a check code calculated by the calculation module (19b) of the receiving device from the received data, and a second wire link (20) connecting the emitting and receiving devices, wherein the receiving device is further configured to transmit an error message to the emitting device if the check codes are not identical, the message passing through the second wire link.