| 摘要 |
PROBLEM TO BE SOLVED: To accurately switch a communication route in accordance with a state of the communication route.SOLUTION: After a communication device 1-1 transmits the plurality of route confirmation request signals for confirming a state of a main route 2 and receives all of a plurality of response signals with respect to each of the route confirmation request signals, if at least one of the plurality of response signals is not received with respect to the plurality of route confirmation request signals, an abnormal counter 15 is caused to start counting from an initial value that is calculated based on a correction value and a value of a normal counter 14 and when a value of the abnormal counter 15 becomes equal to or greater than a switching threshold, the main route 2 is switched to a detour route 3. If all of the plurality of response signals are received with respect to the plurality of route confirmation request signals, the correction value is calculated based on a maximum response time measured by a timer 16, a present correction value and a present value of the abnormal counter 15 and if the value of the normal counter 14 becomes equal to or greater than a value obtained by adding the calculated correction value and a cut-back threshold, the detour route 3 is returned to the main route 2.SELECTED DRAWING: Figure 1 |
