To alter the device constitution without requiring any operator's operation.

An all-identifier table 105 holds the identifier table of slave devices in maximum constitution, an essential constitution table 107 holds minimum required constitution for base station device operation, and when the device is started up, a monitor and control unit 104 gathers the identifiers of mounted slave devices 103 and compares them with the identifier table to decide the mount state; and an operation judgement part 108 compares the recognized mount state with the essential constitution table to judge whether or not the operation is possible and when so, an LED control part 109 makes an LED display device 110 illuminate.