Node-RED + ChirpStack: Build LoRaWAN Flows over MQTT

In the ChirpStack application under Integrations, enable the MQTT integration with the marshaler set to JSON. Every uplink is then published to:

application/{ApplicationID}/device/{DevEUI}/event/up

The message body is the same v4 event you would forward anywhere else. With a working codec on the device profile, the decoded values sit in the object field:

{
  "deviceInfo": {
    "applicationId": "00372e31-0620-4671-8270-237632a4e227",
    "applicationName": "cold-chain",
    "deviceProfileName": "EM300-TH",
    "deviceName": "coldroom-01",
    "devEui": "24e124136b502217"
  },
  "fPort": 85,
  "fCnt": 128,
  "data": "AXVkA2etAARoSw==",
  "object": { "battery": 100, "temperature": 17.3, "humidity": 57.5 },
  "rxInfo": [{ "gatewayId": "24e124fffef54092", "rssi": -51, "snr": 13.8 }],
  "txInfo": { "frequency": 868100000 }
}

Wire the mqtt in node into a function node. The decoded sensor values are in msg.payload.object; the device identity is in msg.payload.deviceInfo. Shape the message for whatever comes next:

// mqtt in -> function: ChirpStack v4 uplink already parsed to an object
var p = msg.payload;
var o = p.object || {};                 // decoded values from the codec

// Stop early if no codec ran (only raw Base64 in p.data)
if (!p.object) {
    node.warn("No decoded object - is a codec set on the device profile?");
    return null;
}

msg.devEui = p.deviceInfo.devEui;        // stable, unique key
msg.topic  = p.deviceInfo.deviceName;    // human label for dashboards

msg.payload = {
    devEui: p.deviceInfo.devEui,
    name: p.deviceInfo.deviceName,
    profile: p.deviceInfo.deviceProfileName,
    ts: new Date(p.time || Date.now()).toISOString(),
    temperature: o.temperature,
    humidity: o.humidity,
    battery: o.battery,
    rssi: (p.rxInfo && p.rxInfo[0]) ? p.rxInfo[0].rssi : null
};

return msg;

From here you fan out: an influxdb out or postgres node for storage, a ui_gauge node for a dashboard, or a switch node that fires an alert when temperature crosses a threshold.

To control a device (a relay, a valve, a thermostat) publish a JSON command to the downlink topic with an mqtt out node. Build the command in a function node:

// function -> mqtt out: enqueue a ChirpStack downlink
var appId  = "00372e31-0620-4671-8270-237632a4e227";
var devEui = "24e124136b502217";

msg.topic = "application/" + appId + "/device/" + devEui + "/command/down";
msg.payload = {
    devEui: devEui,        // must match the DevEUI in the topic
    confirmed: false,
    fPort: 85,             // must be greater than 0
    data: "AQ=="           // Base64 command; ChirpStack encrypts before sending
};
return msg;

Set the mqtt out node's output to JSON (or JSON.stringify the payload yourself). If a codec with an encodeDownlink function sits on the device profile, you can send an object field with readable values instead of data. For Class A devices the command is delivered in the RX window after the next uplink; for Class C devices almost immediately.

Node-RED is ideal for prototyping, light routing and bridging odd protocols. For long-term storage and proper dashboards, send the shaped data on to a time-series store and Grafana, or to ThingsBoard, see ChirpStack to ThingsBoard. We run the broker, the flows and the backups for you as Node-RED managed hosting alongside ChirpStack hosting, so the flows you build stay yours.