Patent ID: 8098987

Claim:
An optical transmitting and receiving apparatus comprising: a transmitting circuit unit comprising a light emitting element and a driving circuit which drives the light emitting element; a receiving circuit unit comprising a light receiving element and an amplification circuit which amplifies a signal received at the light receiving element; and an abnormality detecting unit having a judging unit which judges an occurrence of an abnormality or failure of at least one of the transmitting circuit unit and the receiving circuit unit based on a current value of a measured data obtained from the transmitting circuit unit and the receiving circuit unit and a measured data storing unit which stores a value of the measured data when the judging unit judges that the abnormality or failure occurs in at least one of the transmitting circuit unit and the receiving circuit unit, wherein, when the judging unit judges that the abnormality or failure occurs, the judging unit judges whether an abnormality-failure reporting flag is set or not, if the judging unit judges that the abnormality-failure reporting flag is already set, the abnormality detecting unit clears the abnormality-failure reporting flag and rewrites the current value of the measured data as the value of the measured data when the judging unit judges that the abnormality or failure occurs in the measured data storing unit, when the judging unit judges, based upon a confirmation flag, that a host apparatus has already retrieved the value of the measured data stored in the measured data storing unit, and the abnormality detecting unit maintains a set state for the abnormality-failure reporting flag, and maintains the value of the measured data stored in the measured data storing unit without storing the current value of the measured data in the measured data storing unit, when the judging unit judges, based on the confirmation flag, that the host apparatus has not retrieved the value of the measured data stored in the measured data storing unit, and if the judging unit judges that the abnormality-failure reporting flag is not set, the abnormality detecting unit stores the current value of the measured data as the value of the measured data in the measured data storing unit when the judging unit judges that the abnormality or failure occurs, and sets the abnormality-failure reporting flag.