No data received in uplink event (fPort = 0)

Hi All.

I am facing issue getting data from Lora sensors. I configured my gateway and devices and i can see the uplink and join messages on device data tab. But once i click an uplink message i see data object as null. I checked logs of gateway-bridge,lora server and lora app server but could not find anything. I am attaching the screen sheet.

The device has sent an uplink on fPort: 0 which is being used for mac-commands in the frmPayload field. This means no application payload was sent by the device, but you can still use the rxInfo / txInfo meta-data for other purposes. So it is correct that the data: null.

Dear thanks a lot for your response. I am new to Lora technology. So you mean to say:

“Above issue is a normal behaviour or i need to make some changes?”

For now i can only see join and uplink request every one minute from device on lora app server device data console. But i am unable to figure out why no data is coming.

Will really appreciate your help.

Hi brocaar,

My sensor as per documentation sends data every hour, i saw some data coming:


But when i try to decode it…it cannot be converted to ascii or readable format. I even tried online decoders but no success… Need your insight. I have attached the payload screen shot.


I think we are now mixing two discussions:

  • The you don’t see data
  • How to decode received data

I believe I have answered the first question. For the second question, please see:

It seems, that an regular uplink with metadata confirmed and eventually also device time request is emitted in the backend as:

  • event with fport=0 with data=null
  • event with fport=2 (expected) with data=“expected”

or how do you handle this? I send user-payload with piggy-backed confirmed and device-time-request.

We are running Chirpstack version 3.16.