A device of the present invention incorporates a data block, received from a Communication Module (CM) connected via an interface, into a frame of a specific format in which a preamble for data synchronization is placed at a head, and transmits the frame to the bus while taking only a data block formed in compliance with an arbitrary Communication Protocol (CP) from a series of frames of the specific format that are constituted from signals detected from the bus. When transmitting data to the bus, the device inserts a code indicating the arbitrary CP into a head part of the preamble, and when a signal corresponding to the head part of the preamble detected from the bus is identified as the code indicating the arbitrary CP, it takes a frame with the identified code to transfer a data block within the taken frame to the CM through the interface.