Technical building blocks

gtbdecode

LoRaWAN Payload Decoder & Encoder

Decode and encode a LoRaWAN payload — 900+ TTN devices, Cayenne LPP, hex/base64. Downloadable TTN v3 / ChirpStack v4 codec.

lorawan
ttn
chirpstack
encoder
downlink
hex
base64

Device

Payload

spaces and 0x accepted

fPort

1 – 223

Select a device, paste your payload,
then click Decode.

Understanding LoRaWAN — encode & decode

Get the codec without decoding a frame

Select your device, then expand the “Get the ready-to-use codec” accordion. You get the manufacturer's payload formatter in two variants: TTN v3 (ready for The Things Stack) or ChirpStack v4 (wrapped for the TR013 runtime). The file includes decodeUplink, and encodeDownlink if the vendor provides it.

Encoding a downlink: what is it for?

Configure a LoRaWAN device without going through the Network Server console: send a setpoint ("set valve on"), change a reporting interval, trigger a test command, request a position on demand. The tool builds the binary payload from a structured object, ready to paste into your NS downlink interface (TTN, ChirpStack, Loriot, Actility…).

How do I find the fPort?

The fPort (1 to 223) identifies the message type at application level. Many manufacturers use only one (often 1, 2, 10, 85 or 100). Others use several to distinguish sensor data, alarms and configuration acknowledgements. Check the device datasheet, or look at the f_port field of your frame.

Where do I get or send the payload?

On ChirpStack: frmPayload field (base64) or data in MQTT JSON. On The Things Stack: uplink_message.frm_payload. On Loriot or Actility ThingPark: payload_hex field. In Niagara: nFrame object of the LoRaWAN driver. For a downlink, most NS expect the encoded payload as base64 or hex.

My device is not in the list?

Many generic devices use the Cayenne LPP format (selectable at the top of the list, decoder only). Otherwise, you can contribute to the TTN catalogue with a PR following the contribution guide — the repo is manually resynced on each OpenGTB update.

Encoder coverage

Not all TTN codecs expose the encodeDownlink function. In our catalogue, about half of the devices have an encoder, and ~399 devices also provide clickable downlink examples (Netvox, Milesight, Decentlab, Tektelic…). For the others, the "Encode downlink" tab is automatically disabled.

Codecs from TheThingsNetwork/lorawan-devices under the Apache-2.0 license.