Further, a LOGIN protocol 7, which is the feature of the present invention, operates between the lower layer 4 and the transport protocol layer 5 of the 1394 interface. [0299] In Example 1 in FIG. 47, by providing the LOGIN protocol 7 to a device based on a serial bus protocol (SBP-2) 8 for a peripheral device such as a printer, the peripheral device uses a protocol based on the protocol SBP-2 to