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Exploring OPC: Bridging Industrial Automation and IoT

In the realm of industrial automation and data communication, Open Platform Communications (OPC) stands out as a critical standard. This blog delves into the OPC technology, tracing its evolution from the OPC Foundation’s establishment through to its current pivotal role in IoT deployments. We’ll explore the differences between OPC Data Access (OPC-DA) and OPC Unified Architecture (OPC-UA), and discuss when to use each. Additionally, we’ll highlight the role of control systems engineers in OPC deployments, using Kepware KEPServer as a case study.

A Brief History of the OPC Foundation

The OPC Foundation was established in the mid-1990s with the goal of creating a standard interface to improve communication between various industrial automation devices and control applications. Initially focused on Windows operating systems, the foundation’s scope has expanded dramatically to accommodate a wide range of hardware and software environments, fostering interoperability in the industrial sector.

OPC-DA vs. OPC-UA: Understanding the Differences

OPC Data Access (OPC-DA) is the older of the two standards, designed specifically for real-time data access between control devices and Windows-based applications. OPC-DA handles data in a way that is tightly coupled with the Windows operating system, utilizing COM/DCOM (Component Object Model/Distributed Component Object Model) for communication. This reliance on COM/DCOM makes OPC-DA less flexible in today’s diverse and increasingly networked environments, as it is confined to local networks and often involves complex configuration to work across firewalls and different network segments.

OPC Unified Architecture (OPC-UA) is a more recent development that addresses many of the limitations of OPC-DA. Unlike its predecessor, OPC-UA is platform-independent and does not rely on COM/DCOM, making it highly adaptable to various operating systems and network architectures, including those commonly used in IoT deployments. OPC-UA provides not only data access but also incorporates information modeling, which makes it possible to represent complex and hierarchical data structures in addition to simple data points.

When to Use OPC-DA vs. OPC-UA

  • OPC-DA is typically used in legacy systems where the environment is stable, contained, and predominantly Windows-based. It is suitable for applications that require real-time access at high speeds within a local network.
  • OPC-UA should be used in newer, more complex environments where system interoperability, security, and reliability across heterogeneous networks are required. It is ideal for projects that extend beyond local systems to include cloud services and remote data access, which are common in modern IoT and Industry 4.0 applications.

OPC-UA’s Role in IoT Deployments

OPC-UA plays a crucial role in IoT deployments due to its robust security features, scalability, and flexibility. As IoT ecosystems often involve a vast array of devices and systems needing to communicate securely and reliably, OPC-UA’s platform-independent model offers a seamless conduit for data flows between devices, edge computing layers, and cloud platforms. Its built-in security mechanisms, such as encryption, authentication, and authorization, ensure that data exchanges across the network are secure from unauthorized access.

The Role of Control Systems Engineers – Plant Floor Device-to-Cloud

Control systems engineers are vital in implementing OPC within industrial settings. At Malisko, we design and manage solutions that integrate OPC with existing control systems to enhance data visibility and operational efficiency. An example of a tool we often use is Kepware KEPServerEX, which is an OPC server that provides a bridge between OPC-UA, OPC-DA, and a myriad of industrial protocols. It allows for data aggregation from various sources (including legacy systems), facilitating easy and secure access to real-time and historical data across multiple client applications. KEPServerEX also supports MQTT through its IoT Gateway plugin, which enables the server to translate industrial protocol data into MQTT messages. This capability allows KEPServerEX to function as an MQTT client, pushing data from industrial devices and sensors up to MQTT brokers or directly into IoT applications and platforms that support MQTT. This integration is particularly useful for creating a streamlined path for device-to-cloud data communication,


OPC standards, particularly OPC-UA, are integral to modern industrial automation and IoT ecosystems. They provide the necessary framework for secure, reliable, and efficient data exchange across diverse and distributed environments. As industries continue to evolve with technological advancements, the role of OPC and the control systems engineers who implement it will remain critical to the success of industrial automation and smart manufacturing strategies.


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