OPCd

OPCd is an acronym that is not tied to a single, universally recognized standard. In practice, it is used as an informal shorthand in some industrial automation projects to denote a daemon or service that handles OPC communications, most commonly OPC Data Access (OPC DA) or OPC Unified Architecture (OPC UA).

In typical deployments, an OPCd component acts as a bridge or gateway, interfacing with OPC DA servers (which may rely on Windows DCOM) and exposing data to OPC UA clients, or doing the reverse. It may run on Linux or Windows, depending on the environment. The goal is to enable interoperability between legacy equipment and modern OPC UA software, allowing data collection, monitoring, and control across heterogeneous systems.

Software implementations labeled OPCd may provide features such as data subscription, historical data access, event handling, and security through authentication and encryption. They often rely on established OPC stacks and libraries, such as OpenOPC, FreeOPC, or native OPC UA stacks, and may be released under open-source or proprietary licenses. Documentation and capabilities can vary significantly between projects that use the OPCd designation.

Because OPCd is not a standardized term, its precise meaning and scope are project-specific. Users encountering the term should seek clarification from the developers or project maintainers to understand the intended role, supported protocols, and interoperability guarantees of a given OPCd implementation.