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Integrating SCADA Systems into Unified Namespace

by Kudzai Manditereza
19 min read

Recently, the Unified Namespace (UNS) has seen significant growth, a trend that shows no signs of slowing down. This is largely due to its ability to eliminate data silos, which have historically hindered efficient information sharing. As a result, a new standard for data management and accessibility is being established. This shift allows manufacturing companies to overhaul industrial data management, moving from outdated and inflexible systems to a more flexible framework that supports real-time decision-making and enhances operational flexibility.

The Supervisory Control and Data Acquisition (SCADA) System is a key element in industrial automation architecture. In this article, we'll delve into how it can be integrated into the Unified Namespace, highlighting the benefits and considerations of such an integration.

Challenges of Traditional SCADA Network Architecture

In the traditional industrial automation pyramid, the SCADA (Supervisory Control and Data Acquisition) system operates at Level 2, managing and gathering data from the base levels (0 and 1) of plant operations, which include PLCs (Programmable Logic Controllers) and field devices. It also communicates with higher-level applications like MES (Manufacturing Execution Systems) at the third level.

Incorporating SCADA systems into operations traditionally requires a direct and specialized connection to collect data from plant-floor devices due to incompatible data formats. This could involve interfacing with thousands of pieces of equipment (such as PLCs and HMIs), which is a complex and tedious task.

Challenges of Traditional SCADA Network ArchitectureFurthermore, higher-level systems like MES and ERP (Enterprise Resource Planning) systems do not directly connect to plant-floor equipment but instead interface through the SCADA system. This integration often relies on proprietary interfaces or software development kits (SDKs) to connect with the SCADA, necessitating significant effort to maintain and update these connections while ensuring compatibility. In some manufacturing organizations, the MES system is disconnected from the SCADA system, leading to manual data collection with paper sheets for operational efficiency metrics, like OEE (Overall Equipment Effectiveness), because such organizations lack direct digital integration between MES and the manufacturing processes.

As a result, integrating a SCADA system within a traditional industrial setting leads to a network architecture filled with manual, point-to-point connections that are expensive and challenging to maintain and scale. This setup restricts the organization's ability to efficiently manage and respond to the increasing variety of data sources, leaving companies with hundreds or thousands of point-to-point connections requiring specialized knowledge.

Advantages of a UNS-based SCADA Architecture

Adopting a Unified Namespace for SCADA systems addresses these limitations by establishing an open, standardized architecture for data exchange. This architecture facilitates real-time access to operational data and simplifies the integration process, significantly reducing the costs of connecting disparate systems and devices. 

The MQTT protocol has become the preferred standard for communication within a UNS framework, offering a significant shift towards an open and interoperable environment. Through MQTT and its "Publish-Subscribe" model, UNS allows for a dynamic and loosely coupled data-sharing model. This method enhances the flow of information within the SCADA network and extends across different operational areas within the manufacturing landscape.

At the core of the UNS approach is a real-time, semantically organized data hierarchy that serves as the central repository of all operational data. This singular, reliable data source mirrors the live state and activities of the manufacturing process. It ensures that all connected entities, including the SCADA system, have immediate and uninterrupted access to vital operational information. This setup streamlines the discovery of role-specific data and promotes a more integrated and coherent operational environment.

In the UNS ecosystem, SCADA systems are transformed into active participants within an MQTT-based network, interacting with factory equipment and MES through a centralized MQTT broker. This evolution towards a UNS framework enables SCADA systems to become self-aware entities capable of autonomously integrating new data points without needing manual setup.

ISA 95 Common Data Model with an MQTT BrokerIntegrating your SCADA system with UNS yields several key benefits:

Simplified Integration: Devices and applications easily join the SCADA network, enhancing the overall data-sharing framework without complex setup processes.

Lower Integration Costs: The need for expensive, specialized engineering to merge plant-floor and IT data into the SCADA network is eliminated, reducing overall integration expenses.

Enhanced Agility: Having real-time visibility into the full spectrum of your manufacturing operations enhances your ability to conduct tests, respond swiftly, and execute plans with greater precision and predictability.

Scalability: The decentralized nature of data exchange through a central hub enables the seamless addition of countless nodes, supporting expansive network growth.

Gathering Data into SCADA Systems Using Unified Namespace

SCADA (Supervisory Control and Data Acquisition) systems traditionally obtain data from devices to control processes, collect data, manage alarms, and maintain historical records. This process often involved proprietary device connectivity interfaces to access the necessary data, leading to a tight coupling between SCADA systems and the devices they monitor. Efforts began in the early 1990s to reduce this dependency, notably with the introduction of OPC (OLE for Process Control), which aimed to create a standardized interface for data collection from devices such as PLCs.

Despite these efforts, including the development of OPC UA, the reliance on a polling mechanism for data collection remained a significant limitation. This method is less scalable and poses security risks due to the need for multiple servers with open ports in industrial settings.

The advent of the Unified Namespace offers a new paradigm for SCADA. In this setup, SCADA systems still fulfill their core functions but adopt a different data acquisition and control approach. Specifically, they leverage the Publish-Subscribe communication model in MQTT. This model allows devices on the factory floor to publish their data to an MQTT broker, which organizes this information within the Unified Namespace. SCADA systems then subscribe to this broker to access the data they need when they need it. This approach eliminates the need for SCADA systems to connect directly to each device, thereby enhancing security by reducing potential attack surfaces and improving overall system performance by streamlining the data collection process.

Integrating SCADA Data into the Unified Namespace

The SCADA system interactions with the UNS extend beyond simply gathering data; it actively publishes enriched, contextual data into the UNS for use by other applications and devices. This approach is particularly beneficial in existing (brownfield) setups where devices transmit data to an HMI/SCADA system or a historian. Leveraging this existing data flow for the UNS can be advantageous. The data obtained from SCADA systems is inherently rich in context, making it immediately useful for integration into the UNS. This method also avoids the additional network traffic and security vulnerabilities that arise from introducing new components to communicate with the control layer.

In essence, the SCADA system acts as a sophisticated data hub. It collects and consolidates data from various sources, such as field devices and Programmable Logic Controllers (PLCs), overseeing different aspects of production. By adopting a unified approach to data management, often through a common data model, SCADA systems facilitate the easy identification and assimilation of data into the UNS.

Moreover, SCADA systems are typically designed to interact with Manufacturing Execution Systems (MES) and Enterprise Resource Planning (ERP) systems, making them well-integrated into organizational networks. This integration simplifies the process of elevating data to the enterprise level, thus enhancing overall data governance.

At its core, a SCADA system connects to the UNS to access all necessary data for efficient production management. It also contributes to the UNS by issuing commands for execution by plant-floor nodes.

Additionally, even as SCADA systems engage with the UNS for data exchange, they maintain direct connections for transactional data with systems like MES and historians. Establishing a link between the historian and the SCADA system is generally prudent.

Using MQTT Sparkplug for SCADA Integration into UNS

Integrating a SCADA system into MQTT Sparkplug based Unified Namespace architecture significantly enhances real-time data exchange, system reliability, and interoperability across various devices and applications. The MQTT Sparkplug specification adds a standardized method to use MQTT for industrial applications, ensuring structured data and state management that is crucial for effective SCADA operations. (A useful on-demand related resource is the How to Achieve Data-Driven Manufacturing with UNS and MQTT Sparkplug webinar.)

Integrating SCADA with OT/IT systems in IIoTHere's how SCADA systems integrate in an MQTT Sparkplug Unified Namespace:

Data Collection and Monitoring

SCADA as Subscriber: In an MQTT Sparkplug network, the SCADA system primarily subscribes to topics that devices (sensors, actuaries, PLCs) publish their data. This allows the SCADA system to collect real-time data from various parts of the industrial process.

Edge of Network (EoN) Nodes: Devices or gateways that collect data from sensors or other devices and publish it to the MQTT broker following the Sparkplug specification. The SCADA system monitors these data points for operational insights and anomaly detection.

Control Commands

SCADA as Publisher: While the SCADA system mainly subscribes to data, it can also publish control commands to devices on the network. These commands are sent through the MQTT broker, which then distributes them to the targeted devices or gateways, enabling real-time control of the processes.

Device Management and State Awareness

Birth and Death Certificates: Sparkplug specifies using "birth" and "death" certificates for devices and applications. When a device comes online, it publishes a "birth" certificate to announce its presence and metadata to the network, including the SCADA system. Similarly, a "death" certificate is published when a device goes offline. This mechanism ensures that the SCADA system is always aware of the network's current state and can manage devices accordingly.

Data Efficiency and Network Optimization

Payload Definition: Sparkplug defines a structured payload that includes metrics, data types, and timestamps, ensuring that the SCADA system receives data in a consistent and efficient format. This standardization helps optimize network bandwidth and simplify data parsing and analysis.

State Management: SCADA systems benefit from Sparkplug's state management capabilities, where devices maintain their last known state. This reduces the need for constant polling by the SCADA system, lowering network traffic and improving system responsiveness.

Interoperability and Scalability

Standardized Communication: By adhering to the MQTT Sparkplug specification, SCADA systems can easily integrate with various devices and other systems, regardless of the vendor. This promotes interoperability and flexibility in expanding or modifying the industrial network.

Scalability: MQTT's lightweight protocol combined with Sparkplug's efficient data structure allows SCADA systems to scale up and manage thousands of devices across different geographical locations without significantly increasing network load or complexity.


Integrating SCADA systems into a Unified Namespace framework represents a transformative step towards more agile, efficient, and scalable industrial operations. By moving away from the limitations of traditional architectures, companies can embrace a more interconnected and dynamic data infrastructure, unlocking new possibilities for real-time decision-making and operational flexibility. This integration streamlines industrial data management and paves the way for future advancements in automation and data exchange technologies.

Next up in this series, we discuss how to integrate a historian into the Unified Namespace. Read on. Are you new to Unified Namespace and trying to understand it? Watch our webinar on Achieving Data-Driven Manufacturing with UNS and MQTT Sparkplug.

Kudzai Manditereza

Kudzai is a tech influencer and electronic engineer based in Germany. As a Developer Advocate at HiveMQ, he helps developers and architects adopt MQTT and HiveMQ for their IIoT projects. Kudzai runs a popular YouTube channel focused on IIoT and Smart Manufacturing technologies and he has been recognized as one of the Top 100 global influencers talking about Industry 4.0 online.

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