Platform
Functions
Decoder Functions
Custom Decoders

Customer Decoder Functions

Custom decoders are decoder functions that you can write yourself. This gives you the flexibility to decode LoRaWAN uplink messages that contain a specific set of fields. You can use custom decoders to decode messages that are sent by different devices or to decode messages that contain a specific set of data.

Examples

The following example will generate an output object containing decoded values for STATUS, BATTERY, and COUNT.

example.js
function decoder(input){
    var bytes = input.bytes;
    var fPort = input.fPort;
    
    var output = {
        STATUS: bytes[0] & 0x01,
        BATTERY: (25 + (bytes[1] & 0x0f)) / 10,
        COUNT: (bytes[7] << 16) | (bytes[6] << 8) | bytes[5],
    };
    return output;
}

Output:

example.js
{
  "STATUS": 0,
  "BATTERY": 2.5,
  "COUNT": 0
}

The following example will directly return the same object with decoded values for STATUS, BATTERY, and COUNT.

example.js
function decoder(input){
    var bytes = input.bytes;
    var fPort = input.fPort;
    
    return {
        STATUS: bytes[0] & 0x01,
        BATTERY: (25 + (bytes[1] & 0x0f)) / 10,
        COUNT: (bytes[7] << 16) | (bytes[6] << 8) | bytes[5],
    };
}

Output:

example.js
{
  "STATUS": 0,
  "BATTERY": 2.5,
  "COUNT": 0
}

The following example will return the same object with decoded values for STATUS, BATTERY, COUNT combined with SNR and RSSI values:

function decoder(input){
    var bytes = input.bytes;
    var fPort = input.fPort;
    var metadata = input.metadata;
    var snr, rssi;
 
    if(metadata && metadata.gws && metadata.gws.length > 0){
        snr = metadata.gws[0].snr;
        rssi = metadata.gws[0].rssi;
    }
 
    return {
        STATUS: bytes[0] & 0x01,
        BATTERY: (25 + (bytes[1] & 0x0f)) / 10,
        COUNT: (bytes[7] << 16) | (bytes[6] << 8) | bytes[5],
        SNR: snr,
        RSSI: rssi
    };
}

Output:

{
    "STATUS": 171,
    "BATTERY": 2.7,
    "COUNT": 14348907,
    "SNR": 8.7,
    "RSSI": -40
}

The example metadata used for the example:

{
  "cmd": "gw",
  "seqno": 12345,
  "EUI": "ABCD1234567890EF",
  "ts": 1111111111111,
  "fcnt": 6789,
  "port": 2,
  "freq": 123456789,
  "toa": 21,
  "dr": "SF8 BW125 4/5",
  "ack": true,
  "gws": [
    {
      "rssi": -40,
      "snr": 8.7,
      "ts": 1111111111111,
      "time": "2023-08-16T10:33:53.433Z",
      "gweui": "1111222233334444",
      "ant": 1,
      "lat": 45.123456,
      "lon": -1.234567
    }
  ],
  "bat": 150,
  "data": "abcdef1234567890"
}

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