| 摘要 |
PROBLEM TO BE SOLVED: To improve the accuracy of information related to communication. SOLUTION: When information of a machine on vehicle obtained by communication processing between a machine on a road and the machine on vehicle is written in an IC card (520), an information invalidation flag of this information is turned off (522), and a timer is started (524), and the timer is monitored to monitor whether information of the machine on vehicle is updated for a certain time or not (526). This information of the machine on vehicle is invalidated if this information is not updated for the certain time, but availability of this information is kept if it is updated. Consequently, the flag stored in the IC card is read on the side of the machine on the road to confirm whether data of the IC card is accurately written in the machine on vehicle or not. |
