Unified Namespace (UNS): the complete guide

MQTT is the lightweight messaging protocol that enables real-time data sharing between industrial systems like PLCs, sensors, SCADA, MES, and ERP.

It uses a publish/subscribe model, allowing devices to send and receive live data through a central broker without custom code. When paired with Sparkplug B, MQTT adds context and structure, making integration seamless and scalable—key to eliminating data silos, reducing costs, and accelerating IIoT adoption.

Sparkplug B is a communication specification that works with MQTT to provide context-rich, structured industrial data. While MQTT handles the transport of messages, Sparkplug B defines the payload format, topic structure, and state management, ensuring that data shared across systems like PLCs, SCADA, MES, and ERP is organized, meaningful, and interoperable. This enables auto-discovery of devices, consistent data models, and built-in status monitoring—critical for a reliable, real-time industrial data layer.

Sparkplug B transforms MQTT from a simple messaging pipe into a smart, industrial-grade protocol tailored for IIoT environments. It standardizes how data is published to the UNS, ensuring all connected systems interpret and interact with it correctly, without custom integration logic. This drastically reduces setup time, simplifies scaling, and helps maintain a vendor-agnostic, future-proof architecture, all of which are core to the value of a Unified Namespace.

A PLC (Programmable Logic Controller) is a foundational device that controls machinery and processes at the shop floor level. It collects real-time data from sensors, actuators, and industrial equipment and executes automation logic to control operations. Traditionally, data from PLCs was siloed or accessible only through proprietary interfaces, limiting its visibility to higher-level systems like MES or ERP. Within a UNS, PLCs become data producers, publishing their real-time data—via protocols like MQTT with Sparkplug B—to a centralized, structured namespace that all systems can access.

By integrating PLCs into a Unified Namespace, their data is no longer trapped at the machine level—it becomes available enterprise-wide in real time. This enables seamless coordination between operational technology (OT) and information technology (IT) systems, reducing latency, improving decision-making, and eliminating the need for complex custom integrations. Through UNS, PLCs play a critical role in driving connected, data-driven industrial operations by feeding live, structured information directly into the organization’s digital backbone.

SCADA (Supervisory Control and Data Acquisition) systems serve as both data consumers and producers within the industrial ecosystem. Traditionally, SCADA systems are used to monitor and control processes in real time, collecting data from PLCs and displaying it to operators through human-machine interfaces (HMIs). However, in legacy architectures, SCADA systems often function in isolated silos, with data locked within proprietary protocols or custom integrations. Within a UNS, SCADA systems instead publish and subscribe to live, structured data via MQTT and Sparkplug B, allowing them to seamlessly interact with other systems like MES, ERP, or cloud analytics platforms.

This integration transforms SCADA from a closed control interface into an active participant in the enterprise-wide data layer. Instead of polling for data or relying on custom connections, SCADA systems can receive updates instantly from the UNS and also contribute valuable process data back into the namespace. This approach improves scalability, simplifies integration, and ensures that all relevant systems have access to consistent, real-time information. In a UNS-driven architecture, SCADA becomes a collaborative node that enhances visibility, responsiveness, and coordination across the entire industrial operation.

OPC UA (Open Platform Communications Unified Architecture) is a key interoperability standard that enables structured, secure, and vendor-neutral data exchange across industrial systems. OPC UA provides a common data model and communication framework that allows devices, such as PLCs, SCADA systems, and sensors, to expose their data in a consistent and semantically rich format. When integrated with a UNS, OPC UA helps normalize data at the edge before it is published into the centralized namespace, ensuring that all systems accessing the UNS receive well-defined and contextualized information.

While OPC UA excels at structured, object-oriented data modeling, it typically uses a client-server architecture. In a UNS, it is often paired with MQTT and Sparkplug B to overcome the limitations of polling-based communication. By converting OPC UA data into MQTT/Sparkplug format, it becomes part of a publish/subscribe model, enabling real-time, event-driven data flow across the enterprise. This combination allows organizations to retain the benefits of OPC UA’s rich data models while leveraging MQTT’s lightweight, scalable communication for UNS-based architectures—creating a future-proof, fully integrated IIoT data ecosystem.

ISA-95 serves as a foundational model for organizing industrial data. ISA-95 is an international standard that defines the hierarchy of manufacturing operations, dividing systems and functions into levels—from the shop floor (Level 0–2: sensors, PLCs, SCADA) to enterprise systems (Level 4: ERP). Within a UNS, this model is used to structure the namespace logically, often by reflecting the ISA-95 levels in topic hierarchies (e.g., Enterprise/Site/Area/Line/Cell). This structured naming ensures that all systems and users accessing the UNS can navigate and interpret data in a standardized, intuitive way.

By aligning the UNS with ISA-95, organizations create a contextual and scalable data model that bridges the gap between operational and business systems. It provides a shared understanding of how data is organized and where it originates, enabling seamless integration, better data governance, and faster troubleshooting. Instead of treating ISA-95 as a rigid architectural blueprint, the UNS uses it as a semantic framework, giving structure to real-time data flowing from devices to applications, while supporting flexibility in modern IIoT environments.