Downlink bytes shown in console do not match the actual message

[interravikram]

Hi all,

I was just trying to get my downlink tested when I realized the bytes sent to the device do not match the downlink I want to send. It looks wrong…
The uplink shows the bytes correctly in the console.

I initially tried scheduling a downlink via the MQTT integration. The bytes shown in console do not match the bytes sent on the MQTT downlink channel. See below.

{
   "downlinks":[
      {
         "f_port":15,
         "frm_payload":"JwEAAAAAAQGAgA==",
         "priority":"NORMAL"
      }
   ]
}

This above downlink schedule message was sent on the MQTT topic v3/logr@ttn/devices/505275339/down/replace

It unfortunately gave the following downlink in the console : 743DF9BF4CBECADC50A8 on FPort 15. The FPort is correct, but the base64 payload was : JwEAAAAAAQGAgA==, it should have sent bytes 27 01 00 00 00 00 01 01 80 80 see here

Then, I tried using the downlink scheduler directly from the application frontend. I tried sending payload 0x00 to test a basic approach. Same problem, it printed incorrectly in the console 0x49, see screenshots below.

Any ideas ?

I will now try to see on the device if the bytes received are also incorrect, or if it is only a problem on the console frontend.

Maybe I am also not aware of something (downlink bytes are shown encrypted on the frontend, on purpose ?). It’s just that : it used to be shown “correctly” in the past.

Thanks for your help

[interravikram]

Hi all,

I could see the bytes received on my device, and they actually match what I wanted to send. The problem is then not that big, but I am still interested in knowing what is happening on the console?

Thanks

[tmkdoguscan]

Hi there,

I have been using the TTN v2 and did not have occasion to use the v3 a lot. Recently I’m back on v3 and I realised the same thing.

• The payload I’m posting is actually : 57 00 03 01 D5 02 93

• The payload showed on the console : C0 F4 67 09 B0 73 E3

Why the downlink payload that I’m composing is not showed on the console as it is ? However, the payload is received by the sensor as it should be… Can anyone explain please why ?

Thanks.

[cprovidenti (Cesar A Providenti)]

What’s shown on the console is the encrypted payload.

[jfmateos]

You can use this service (https://lorawan-packet-decoder-0ta6puiniaut.runkit.sh) to decode the raw_payload of your downlink:


Kind regards from Madrid