| 摘要 |
<p>PURPOSE:To facilitate a detection of a faulty area, by switching the using system to a stand-by system when the using system has a fault and at the same time reporting the system switcing to a monitor device above that time through a receiving station or a transmitting system. CONSTITUTION:For instance, a data transmitting device 2 receives a data frame and performs an FCS check when data is transmitted to the device 2 from a data transmitting device 4. Then no answer frame is sent back to the device 4 if an error of the data frame is detected. The device 4 detects the time-out if no answer frame is sent back and then transmits again the same data frame. When the error detecting frequency through the FCS checking exceeds a prescribed level, the device 2 regards that the using system is not serviceable and then switches the using system to a stand-by system as well as to inform this switching to a monitor device 1. On the other hand, the device 4 decides the failure of retransmission and then informs this fact to the device 1 by means of an information field I.</p> |
