In a system in which an IEEE 1394 interface is provided for an IRD, connected equipment can be easily selected and the operability is improved. Data can be transmitted among the equipment by providing the IEEE 1394 interface for the IRD. For example, five equipment units are selected from the equipment connected to the IEEE 1394 interface and node ID numbers are allocated to the five equipment units and registered. Thus, even if the equipment is removed from the interface and connected again, the IRD can recognize the equipment. The registration may easily be changed by user input. When the registration is changed, the change of the registration is inhibited among equipment units in which a program reservation has been set or the connected equipment. Thus, even if the registration is changed, an erroneous operation does not occur.