| 摘要 |
<p>PURPOSE:To simplify a device while securing the time synchronism precision by fetching time data from a subordinate control unit when a main control unit is started up and fetching the time data from the main control unit at a normal time. CONSTITUTION:When the main control unit 9 is started up, initial time 11-1 is obtained from the internal timer 15 of the subordinate control unit 10 which is continuously in time clocking operation and sets in the internal timer 12 of the main control unit 9 to enable the use of a device which has no backup function as the internal timer 12 of the main control unit 9. Further, the time 11-2 of the internal timer 12 is normally sent from the main control unit 9 to each subordinate control unit 10 to perform time synchronization among units. At this time, the subordinate control unit 10 possibly has a large error in received correction time 11-2 attending on data transmission, so after the propriety of the correction time 11-2 is confirmed based on the internal time 11-3, the time is fetched to the internal timer 15.</p> |
