OPCs

OPC refers to a family of standards for open connectivity in industrial automation, enabling data exchange between devices, controllers, historians, and software from different vendors. The name originated as OLE for Process Control and was later shortened to Open Platform Communications. The OPC Foundation administers the specifications and the interoperability certification program, while vendors implement OPC servers and clients to enable cross-vendor communication.

Historically, OPC Classic includes Data Access (OPC DA), Alarms and Events (A&E), and Historical Data Access (HDA). These standards typically relied on Microsoft COM/DCOM and were primarily Windows-based, using a client-server model in which clients request data from servers. OPC XML-DA provided an XML-based wrapper to enable data exchange over standard web protocols. OPC DA/HDA/A&E are still in use, particularly in legacy systems, but many deployments are migrating to OPC UA.

OPC Unified Architecture (OPC UA) represents the modern, platform-independent evolution. It uses a service-oriented architecture, supports multiple encodings (UA Binary for performance, XML/JSON for interoperability), and defines a rich information model in an address space that describes devices, data types, and relationships. OPC UA includes built-in security features such as authentication, encryption, and auditing, and is designed to work across local and wide area networks, including industrial IoT and cloud environments.

Applications and impact: OPC standards enable interoperability across devices from many manufacturers, facilitating data collection, monitoring, control, and analytics in manufacturing, energy, oil and gas, water treatment, and building automation. The OPC Foundation maintains compliance tests to promote interoperability and reduce integration risk. Adoption varies by industry and legacy constraints, with many sites running a mixed OPC DA and OPC UA ecosystem during transition.