PURPOSE: To decrease a load at the time of coping with a fault by selectively outputting only a necessary part in the trace analysis of a CCS in a visible and easily editing system.

CONSTITUTION: A trace file 24 and a CCS trace file editing/output device 26 are provided, the trace file 24 stores input/output information when a CCS 22 communicates, a CCS trace file editing/output device 26 freely selects the sub-file of the trace file 24, and edits and outputs it. Consequently only the necessary part in the trace analysis of the CCS can be outputted in the visible and easy editing system. Thus the trace analyzing time is reduced, and the labor spent for coping with the fault can be decreased.