PURPOSE: To find out mis-setting of address or defective multiplex transmission line easily by comparing input address data with an adderess transmitted from a transmission controller.

CONSTITUTION: When the system is initially started, corresponding address data are fed from a personal computor 5 to respective controllers. The personal computer 5 compares the address data with addresses transmitted from transmission controllers 3a, 3b. Reset of address through a switch, wiring check of multiplex transmission line, repair and the like are carried out according to the content of displayed trouble. By such arrangement, erroneous calculation of charge due to mis-setting of address or mis-wiring can be prevented.