To accurately extract all faults which occur within a unit as a hard signal and to completely cut off a communication of the unit wherein the faults occur according to the signal so as not to disturb communications between other units.
In the communication system control apparatus composed of a plurality of control units 10A, 10B... connected by a communication bus 100 to make two-way communications possible, when abnormality occurs, each control unit detects the abnormality and when the abnormality is detected, an abnormality detecting signal is generated. According to the generated abnormality detecting signal, a communication signal cutoff means 31 is operated to cut off a transmission of a communication signal to be transmitted from the same control unit (control unit 10A, for example). Then, from a receiving status of a communication signal in the other control unit (control unit 10B, for example) except for the control unit where the abnormality is detected, the occurrence of the abnormality in the control unit is identified by the relevant other control unit.
MANAKA TOSHIO
SAITO HIROYUKI
YOSHIDA TATSUYA
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