These classic specifications have served the industry well, but as technology has evolved, so did the need for OPC specifications. In 2008, the OPC Unified Architecture (UA) was developed as a platform independent service-oriented architecture to address the issue of platform interoperability by using Web services-oriented architecture (SOA) in place of .NET and DCOM. UA significantly expands the use of OPC to include non-Windows platforms such as field controller, cellphones, UNIX, and Linux enterprise servers, as well as Window servers.
The biggest difference between OPC classic and OPC UA is that OPC UA doesn’t rely on OLE or DCOM technology (windows), making it possible to implement OPC UA on any platform, such as Apple, Linus, or Windows. Another important UA feature is its ability to use structures and models, so data tags or points can be grouped and given context, making governance and maintenance easier.
Copyright: Cybersecurity & Infrastructure Security Agency (CISA)