A first device is provided with a communicator having a first interface function and a second interface function defined in an asymmetric interface standard. A second device is connected to the first device. The first device detects whether the second device has at least one of the first interface function and the second interface function. Data is transmitted from the first device to the second device, through use of the first interface function, in a case where it is detected that the second device has the second interface function. A signal for processing the data is transmitted from the first device to the second device, through use of the second interface function, in a case where it is detected that the second device has the first interface function.