Milesight EM500-UDL: Outdoor LoRaWAN Ultrasonic Level Sensor

function decodeUplink(input) {
  var bytes = input.bytes;
  var data = {};

  for (var i = 0; i < bytes.length; ) {
    var channel = bytes[i++];
    var type = bytes[i++];

    if (channel === 0x01 && type === 0x75) {          // battery (%)
      data.battery = bytes[i]; i += 1;
    } else if (channel === 0x03 && type === 0x82) {   // distance (mm)
      data.distance = readUInt16LE(bytes, i); i += 2;
    } else if (channel === 0x83 && type === 0xe9) {   // distance + mutation alarm
      data.distance = readUInt16LE(bytes, i) / 10;
      data.distance_mutation = readUInt16LE(bytes, i + 2) / 10;
      data.distance_alarm = bytes[i + 4];
      i += 5;
    } else if (channel === 0xff) {                    // device info (version, SN, status)
      break;
    } else {
      break;
    }
  }
  return { data: data };
}

function readUInt16LE(b, i) {
  return (b[i + 1] << 8) | b[i];
}