The object of the present invention is to provide a controller and a system having a highly reliable fail safe function. An ATP device which generates control data for the two systems from an ATP command speed signal, duplicates the logic unit in the ATP device so as to process each control data, provides at least two CRC data for checking the control data for each system, and changes the CRC data of the opposite logic units or selects one of the two according to the content of a failure detection signal from each of the duplicated logic units. It is realized to check the control data and the operation of each logic circuit and only when all the data, circuits, and elements operate normally, an output signal for controlling the object to be controlled is outputted and when a failure is detected in a part, an output signal is outputted. Therefore, when a failure occurs, a fail safe function for controlling on the safety side is made possible.