Check the diagnostic information, which shows that the received optical power is low, with a threshold of -3 to -23. Once it exceeds the threshold, an alarm will be triggered. The five parameters have basically decided whether the opti al module can work normally. If one of the five parameters is abnormal, ONU registration will be abnormal or packet nt are all for the PON port. The light reception power is for an ONU, that is, it is for a. The parameters of optical module include the light transmission power, the light reception power, the temperature, the power-supply voltage and the bias current.