OPC

Open Platform Communications (OPC) is a family of standards for industrial automation data exchange designed to enable interoperability between devices, controllers, and software applications such as PLCs, SCADA systems, historians, and enterprise software. The standards are maintained by the OPC Foundation, a non-profit organization that coordinates development, testing, and certification of OPC specifications.

OPC originated as OPC Classic, based on Microsoft COM/DCOM technology. It defined several specifications, including Data Access for real-time data, Alarms and Events for signaling conditions, and Historical Data Access for retrieving stored data. An XML-enabled variant, OPC XML-DA, extended access over web services to enable cross-platform clients. OPC Classic relies on Windows-specific components, which limited portability and scalability in mixed environments.

OPC UA (Unified Architecture) is the platform-independent successor designed to overcome the limitations of OPC Classic. It uses a service-oriented architecture and a flexible information model to support secure, reliable data exchange across diverse systems and network topologies. OPC UA provides robust security features such as encryption, authentication, and user access control, along with scalable architectures suitable for embedded devices up to enterprise servers. It supports multiple transport encodings, including binary and XML, and enables custom information models in addition to standard objects.

OPC has achieved broad adoption across manufacturing, energy, building automation, and process industries, facilitating integration of field devices with enterprise software. Certification programs help verify interoperability among OPC-compliant products, promoting vendor-neutral interoperability and long-term backward compatibility within mixed environments.