PURPOSE:To speedily and easily confirm whether or not independent indication numbers are set for respective equipments of a system by accumulating return signals from the equipments. CONSTITUTION: A transmitting means 9 transmits a confirmation signal for a use/nonuse state through a transmission line 4 as to an optional indication number usable in a system according to a control means 12. constituent equipments of the system receive the confirmation signal and an equipment having the corresponding indication number sends a return signal. The received signal is transmitted to the control means 12 through a means 10 and the means 12 accumulates the number of return signals. Those operations are repeated as many times as required and the accumulation result is displayed on a display means 11.
