DETECTING SYSTEM FOR EQUIPMENT SELECTION ERROR

PURPOSE:To clearly detect the double setting of the same equipment address or an error for the equipment selection due to the failure of a selection circuit. CONSTITUTION:By monitoring a signal line on a bus interface that is useful simultaneously for all of the equipments 2a-2n to be selected by the equipment to be selected, it is detected that the equipment selection is abnormal. In other words, the presence of a selection and response signal ADI on a selection and response line 3c are investigated. When the selection and response signal ADI is present regardless of the issuing of the equipment address coincided with its own set address from a selection device 1, an equipment selection error is issued recognizing the other devices to be selected as the same equipment addresses.