FOT Lesson: FTTH ONT’s LED in actual application

LED status & it’s function

There are many LEDs in FOT ONT, such as CATV, WPS, WLAN, USB, Tel1-Tel2, LAN1-LAN4, LOS/PON, POWER.

  Our global customers can simply troubleshoot by follow the vendors’ ONT LED status. So at first we need to introduce with every ONT LEDs & it’s function.
  Note: In the preceding table, if the LED status is marked “Blinking” but the frequency is not specified, it indicates that the blinking frequency of the LED is determined by the data traffic transmitted.

CATVonThe CATV function is enable and CATV signals are received
offThe CATV function is disable and CATV signals are received
WPSonThe WPS function is enabled
BlinkingAt least one Wi-Fi terminal is accessing the system.
OffThe WPS function is disabled
WLANonThe WLAN function is enabled
BlinkingData is being transmitted.
OffThe WLAN function is disabled
USBONThe USB port is connected and is working in the host mode, but no data is transmitted.
Fast blinking (Twice per second)Data is being transmitted.
OffThe system is not powered on or the USB port is not connected.
TEL1 - TEL2OnThe connection between the TEL port and the voice server has been set up.
Fast blinking (Twice per second)The voice service of the TEL port is established and is in the off-hook or ringing state.
Slow blinking (Once two seconds)The voice of service ot the TEL port is registering.
OffThe connection between the TEL port and the voice server is not set up.
LAN1 - LAN4onEthernet connection is normal.
BlinkingData is being transmitted through the Ethernet port.
OffEthernet connection is not set up.
LOS/PONSee following Table (2).
PoOWERGreenThe GPON erminal is powered on.
OrangeThe backup battery is supplying power.
OffThe GPON Terminal is powered off.

Description of LEDs:

PON and LOS are GPON LEDs. The status of PON and LOS reflects the connection between GPON terminal and the optical line terminal (OLT). The following table describes the status of the PON and LOS LEDS.

No.PON StatusLOS StatusDescription
1OffoffThe ONT is disabled by the OLT.
2Fast blinking (Twice per second)offThe ONT tries to create a connection to the OLT.
3OnoffA connection is created between the ONT and the OLT.
4OffSlow blinking (Once two second)The receive optical power of the ONT is lower than the receiver sensitivity.
5Fast blinking (Twice per second)Fast blinking (Twice per second)The OLT detects that the device is a rogue ONT.

When the LEDs are in the states as described in related user manual, that is, the OLT detects that the device is a rogue ONT, rectify the fault in time and replace the rogue ONT.

The ONT LED status FAQs:

The POWER LED is off.

  • Check whether the ON/OFF button on the rear panel is pressed.
  • Check whether the power adapter adapter matches the GPON Terminal.
  • Check whether the power connection is correct.

The LOS LED is blinking.

  • When the LOS LED blinks slowly, check whether the pigtail fiber is connected normally and whether the optical connector is contaminated.
  • When the LOS LED blinks quickly, check whether the GPON terminal transmits optical signals normally.

The PON LED is off

  • Check whether the optical fiber is properly connected to the optical port.
  • The GPON terminal fails to register with the OLT. Contact the service provider for help.

The CATV LED is off.

  • Check whether the network cable delivered with the device is used.
  • Check whether the network cable is connected properly.
  • Check whether the LED of the network adapter is on.
  • Check whether the network adapter works normally.

The TEL LED is off.

  • Check whether a voice user is configured and enabled.

The WPS LED is off.

  • Check whether the WPS service is started.

The WLAN LED is off.

  • Check whether the WLAN service is started.

The USB LED is off

  • Check whether the connection of the USB device is correct.
  • The phone does not ring when it receives a call, but the communication is normal when the phone is in the offhook state.
  • The ONT provides a maximum ringing current voltage of 60 V AC. Please check that the ringing current voltage of the phone does not exceed 60 V AC; otherwise change another phone.
How to reset the GPON terminal?
Press the Reset button by using a sharp-ended object and then release the button. Press the button to reset the device: press and hold the button (longer than 10s) to restore the device to the default setting and reset the device. If the LED is off and then on again, it indicates that the system is reset successfully.

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