| 摘要 |
PROBLEM TO BE SOLVED: To prevent control due to errors in data in advance by detecting a fault in mutual controllers only through a transmission line, without the use of an exclusive cable through which occurrence of a fault of the controller is delivered. SOLUTION: In a data transmission system, where one controller 1 and other controller 2 interconnected by a transmission line 3 transmit data with each other, the one controller transmits quality data '0', '1' cyclically (4) to the other controller, the other controller transmits the quality data via an inverting means 8 that confirms soundness of the other controller, logic means 6, 7 process the transmitted quality data and the returned quality data so as to detect normality and abnormity of the controllers or the transmission line. In this case, only when the respective controllers or the transmission line is normal, are the quality data updated (5). Furthermore, time limit operating means 9, 10 provided in the other controller discriminate the quality data to be in error, when the quality data are not replaced cyclicly over a prescribed time. |
