PURPOSE: To prepare a device mount list again automatically by registering device recognition information noticed from a slave processor.

CONSTITUTION: A master processor 1 prepares a device mount list on which communication information for communication of each of slave processors 3-7 is stored. In this case, the master processor 1 is provided with making inquiry of the slave processors 3-7 about a device type and recognizing the attribute of the slave processors 3-7 and a means generating the device mount list for the slave processors 6,7 of a bus 8 connecting and for the slave processors 3-5 connecting to the bus 8 via an interface converter 2 in two stages. In this case, the interface converter 2 is provided with two modes, the transparent mode and the nontransparent mode and with a means operated in the nontransparent mode only at the generation of the device mount list and in the transparent mode for the other case.