| 摘要 |
PURPOSE:To accurately detect a defective function module on a common bus by permitting a micro processor to sequentially prohibit the outputs of the abnormality detection signals of the function modules when abnormality occurs and to specify the function module in which abnormality has occurred. CONSTITUTION:When CPU 1 has detected a fault through a fault signal line (b) in the transfer of data with the function modules 2-4, a fault output control circuit 8 first prohibits the output of a fault detection circuit 5 by using an output control gate 11 by designation from CPU 1 by a command using the common bus (a). When CPU 1 continuously detects the fault in such a state, it is detected to be abnormality except for the function module 2. Consequently, the prohibition of the function module 2 is released, and a similar prohibition operation is performed as to the function module 3. When CPU 1 does not detect the fault, the function module 3 is judged to be abnormal, and the function module 4 is to be abnormal when the fault is detected due to prohibition in the function module 3. Thus, the abnormal function module on the common bus can be detected accurately. |
