Operator-side system and mode file identifying method

A storing unit stores a map indicating correspondences between keywords representing states of a vehicle and faulty conditions of the vehicle. A keyword setting unit sets the keywords in response to the vehicle as a recorded object. Aprocessing unit identifies the faulty condition corresponding to the set keywords by searching the storing unit. Then, the mode file corresponding to the identified faulty condition is decided as the mode file to be set in a data recording system, based on correspondences between the previously-set faulty conditions and data contents to be recorded and conditions.