| 摘要 |
<p>PROBLEM TO BE SOLVED: To make possible to utilize data of the results of self-diagnosis under a state of high reliability even upon occurrence of a disturbances, e.g. an abnormal drop of power supply voltage. SOLUTION: Power devices 31, 32 and 33 transmit data indicative of the results of self-diagnosis to a controller 21 by serial communication through a communication line 23. When a low voltage detecting circuit 24 detects an abnormal drop of power supply voltage, a CPU 22 neglects the serial communication data. The data is neglected until a counter 26 counts the number of times of serial communication and communication with all power devices 31, 32 and 33 makes a round. Even in such a case as the effect of power supply voltage drop remains in the form of a communication delay after the power supply voltage is recovered, data having a possibility of abnormality is neglected and only the data of self-diagnosis having high reliability can be utilized.</p> |
