MQTT and SCADA Integration Guide

This guide explains how to move plant-floor data from field devices into MQTT consumers and SCADA systems without creating an unmanageable topic tree. The main objective is predictable naming, payload quality and alarm-friendly behavior.

Reference architecture

• Collect values from the device or protocol gateway on the local industrial network.
• Normalize tags into a consistent MQTT namespace that reflects site, line, asset and signal.
• Expose the same normalized model to SCADA through the preferred northbound connector.

Topic structure recommendation

Use a fixed hierarchy such as site/line/asset/signal. Avoid dynamic topic fragments that depend on human-entered labels because they break subscriptions and alarm mappings over time.

1. Define the asset namespace before any payload mapping starts.
2. Separate telemetry, alarms and command channels so subscribers can apply different retention and QoS rules.
3. Publish quality metadata including timestamp, source and bad-quality markers when values are uncertain.
4. Map SCADA tags from the normalized namespace instead of directly from raw device addresses.

Payload hygiene

• Keep units, scaling and engineering ranges explicit.
• Use consistent booleans and enumerations across all assets of the same type.
• Document whether timestamps represent sample time or publish time.

Validation checklist

Before sign-off, prove that a new value appears in MQTT, reaches the SCADA view, updates at the expected rate and preserves the same engineering meaning in both places.