A. Optical cable on-off detection: Use a laser flashlight, sunlight, or illuminator to illuminate one end of the optical cable connector or coupler; see if there is visible light at the other end? If there is visible light, it means that the optical cable is not broken.

B. On-off detection of optical fiber connection: use laser flashlight, sunlight, etc. to illuminate one end of the optical fiber jumper; see if there is visible light at the other end? If there is visible light, it means that the optical fiber jumper is not broken.

Is the half/full duplex method wrong?

Some transceivers have FDX switches on the side: full duplex; HDX switches: half duplex.

Detected with an optical power meter

The luminous power of the optical fiber transceiver or optical module under normal conditions: multi-mode 2Km: between -10db-18db; single-mode 20km: between -8db-15db; single-mode 60km: between -5db-12db; if When the luminous power of the optical fiber transceiver is between: -30db-45db, it can be judged that there is a problem with the transceiver.