LoRaWAN Gateway to SCADA: The MQTT Bridge Guide

For decades, the factory floor spoke Modbus. Today, the language of the Industrial IoT is MQTT. Bridging this gap is the key to modernizing operations. This guide explains how to use a LoRaWAN gateway as the translator between wireless field sensors and your central SCADA system. We explore the "MQTT Bridge" architecture, where the gateway publishes decoded sensor data directly to a broker. We compare this "Push" model against the legacy "Poll" model of Modbus, highlighting why MQTT is faster, more efficient, and the preferred standard for Industry 4.0.

Industrial automation is colliding with the Internet of Things.

On one side, you have SCADA systems controlling pumps and valves. On the other side, you have wireless LoRaWAN sensors monitoring vibration and temperature. The challenge is connecting them. SCADA systems expect wired data; sensors send wireless radio packets.

The solution is the LoRaWAN gateway.

Modern industrial gateways are no longer just packet forwarders; they are protocol converters. By using MQTT (Message Queuing Telemetry Transport), you can turn your LoRaWAN gateway into a native data source for your industrial dashboard. This guide shows you how to bridge the gap.

Modbus is the grandfather of industrial protocols. It works by "Polling": the server asks, "Do you have data?" every second. This is inefficient for battery-powered sensors that only sleep 99% of the time.

MQTT is the modern alternative. It uses a Publish/Subscribe model.

• The Client: Your LoRaWAN gateway acts as the Publisher.
• The Broker: A central software (like Mosquitto or HiveMQ) that sorts messages.
• The Subscriber: Your SCADA system (like Ignition).

The Benefit: The LoRaWAN gateway only speaks when it has something to say. When a sensor reports a temperature spike, the gateway immediately "Publishes" that data to the broker. The SCADA system receives it instantly. It is faster, uses less bandwidth, and scales to thousands of devices.

To build this, your LoRaWAN gateway must be running an Embedded Network Server (or an Edge App) capable of decoding data.

1. Ingest: The LoRaWAN gateway receives the raw RF packet (0x01A4).
2. Decode: The internal decoder converts it to a value (420).
3. Format: The gateway wraps it in JSON: {"sensor_id": "pump-1", "value": 420}.
4. Publish: The LoRaWAN gateway sends this JSON to the MQTT Broker on a specific topic: factory/pump-1/pressure.

Configuring a Robustel LoRaWAN gateway for MQTT is straightforward via the RobustOS interface.

1. Enable the Service: Go to Services > Data Output.
2. Select Protocol: Choose MQTT.
3. Broker Address: Enter the IP address of your SCADA/MQTT Broker.
4. Topic Structure: Define the path. For example, lora/{{DevEUI}}/up. This dynamic tag ensures every sensor gets its own unique channel.
5. Authentication: Enter the username and password required by your broker.
6. TLS: If sending data over the public internet, upload the CA Certificate to the LoRaWAN gateway to encrypt the link.

Once the LoRaWAN gateway is publishing, you need to display it. In a platform like Inductive Automation's Ignition:

1. Install the "MQTT Distributor" or "Engine" module.
2. Point it to the same Broker.
3. Ignition will automatically discover the tags. You will see a folder structure appear: factory > pump-1 > pressure.
4. Drag and drop that tag onto your screen.

You now have a live wireless sensor reading on your HMI, powered by the LoRaWAN gateway.

You can use Modbus TCP (as discussed in previous articles), but MQTT offers richer data.

• Modbus: Only sends a number (420). You lose context.
• MQTT (JSON): The LoRaWAN gateway can send the number (420) plus the battery level, signal strength (RSSI), and timestamp in a single packet. For complex IoT deployments, this metadata is crucial for maintenance, and only MQTT carries it efficiently.

The days of hard-wiring every sensor to a PLC are ending. The LoRaWAN gateway combined with MQTT allows you to deploy a flexible, scalable sensor network overlay on top of your existing plant infrastructure.

By bridging RF data directly to your SCADA system, you give your operators the visibility they need without the cost of conduit and copper. It is the efficient, secure path to Industry 4.0.