What is OPC Unified Architecture (OPC UA)?
OPC Unified Architecture (UA) is a platform-independent, service-oriented protocol design that integrates all the functionality of the individual OPC Classic specifications into one extensible specification framework. This approach accomplishes functional equivalence to OPC Classic, with all COM OPC Classic specifications mapped to UA. It also achieves platform independence with support for ARM/x86, Windows/non-Windows, and security, including encryption, signing, and authentication. Extensibility, the ability to add new features without affecting existing applications, and information modeling, which creates standard and custom information structures from unstructured data, are also key components of OPC UA.
OPC Classic vs. OPC UA
OPC UA provides a single, secure, and reliable cross-platform framework for accessing a variety of data. In OPC “Classic,” each protocol is its own standard with no relation to or compatibility with one another. Services (read, write, etc.) unique to each protocol are used to access unique data within each model. With OPC UA, services are abstracted from the information models they can access. Client applications programmed to be aware of the information model they want to access can use a common set of services to obtain the data.
History of OPC UA
First released in the mid-1990s, the original OPC standard abstracted PLC-specific protocols (such as Modbus, DeviceNet, etc.) into a common API allowing HMI/SCADA systems to interface with “middleware” that would convert generic OPC read/write requests into device-specific requests. The technology took hold, and an entire industry of products emerged that allowed systems to be implemented using best-of-breed products seamlessly interfacing via OPC. First iterations of the OPC standard were restricted to Windows operating systems, and thus the acronym OPC was derived from “OLE (object linking and embedding) for Process Control.” The OPC Classic specifications, as they are now known, have been widely adopted across multiple industries. As manufacturing systems and organizations evolved, industries faced new challenges, including security and data contextualization. The OPC Foundation developed OPC UA to address these needs and to provide a feature-rich, extensible platform that was scalable and future-proof.
OPC UA specifications
The OPC UA specification offers the same features as OPC Classic, plus modeling and behavior specifications, such as Data Access, Historical Access, Alarms and Conditions, and pub/sub communication. It also supports specifications like Services, Mappings, Profiles, and Security. OPC UA's extensibility with the OPC UA Client driver allows for easy addition or modification of specs without affecting existing UA-enabled applications.
Introducing UA Gateway
Kepware is the industry leading connectivity platform, providing a single source of industrial automation data to across applications. For enterprises that need to bridge the gap between different OPC UA servers, the new OPC UA Gateway facilitates streamlined data flow, enabling namespace aggregation, federation and securing of structured data throughout the enterprise, exclusively configured via Kepware+.
OPC UA capabilities
Fast and Secure Communications
The fast and secure OPC UA Binary TCP protocol offers industrial HMI, SCADA, and other OT systems the security, flexibility, and performance required for modern process control and data acquisition.
Roles-Based Data Access
OPC UA’s built-in authentication features allow applications to apply granular, roles-based access controls for any object present within the OPC UA server.
Secure Data Tunneling
OPC UA is well-suited to safely move industrial data through secure network barriers like firewalls. As part of the base standard, OPC UA offers client/server protocol support with only a single, user-selected TCP port utilized to host the connection on the server side. This limits the number of inbound ports required for data access between secure layers and upper network levels, increasing security and reducing business risk.
Server Aggregation
The flexibility of OPC UA namespaces allows node IDs from external sources, including other OPC UA servers to be automatically sourced and rendered in a single, concise address space, reducing integration time and system complexity.
Digital Transformation Ready
OPC UA offers critical features necessary for safe and secure connectivity and data acquisition for Industry 4.0 efforts, including access controls, encryption, data contextualization, and modeling.
UA security
Transport
OPC UA defines multiple transport types like high-performance OPC-binary over TCP or the heavier, but more open, JSON encoding type over Web Sockets.
Message Signing
Each message exchanged by server and client includes a unique cryptographic thumbprint, allowing client and server to verify the integrity of received messages.
Session Encryption
Messages between OPC UA clients and servers can be encrypted and securely transmitted using a variety of best-in-class encryption algorithms.
Sequenced Packages
Assigns an unalterable sequence to exchanged messages, eliminating the possibility of message replay attacks.
Authentication
OPC UA parties identify themselves through industry-standard X.509 digital certificates, allowing unambiguous determination of identity and granular control of permitted connections.
User Control
OPC UA supports the exchange of user information like usernames and passwords, web tokens, and digital certificates that server applications can use to granularly control activities like reads, writes, and browsing.
Auditing
OPC UA allows applications to create activity trails, or audit logs of commands issued by clients and messages sent by servers.
OPC UA and Industry 4.0
The OPC UA specification facilitates the interoperability and information exchange required for successful Industry 4.0 efforts. Its ability to provide modern, secure cross-platform data exchange, coupled with support for client/server and pub/sub messaging types, creates an opportunity for diverse network topologies and application stacks. Its support for standard and custom information models allows an organization to provide structure to unstructured data as close as possible to the systems generating the data in the model and format that best fits the organization’s unique needs.
Key OPC UA Security Concepts
These key OPC UA Security concepts will help you understand how your data is protected.