Abstract: In a system in which a plurality of devices are connected by using a digital interface bus, in order to readily and easily cope with a specific device when the specific device malfunctions, the system, in compliance with a predetermined digital interface in which a predetermined identification code, a processing target discriminating code, a processing field prescribing code and processing executing information are set, includes means 12, 23 for recognizing the identification code, means 14, 22 for discriminating the processing target when the identification code is recognized and information processing means 16 to 19, 24, 25 for executing the processing in accordance with the processing field if the processing target contains its own device, wherein a defective device can be specified and repaired with ease.