Open Platform Communications Unified Architecture (OPC UA)

What is it?

Open Platform Communications Unified Architecture, or OPC UA, is a cross-platform data exchange standard for industrial automation and communication on a machine-to-machine or PC-to-machine basis. Unlike its predecessor OPC DA, the OPC UA standard is generally available and implemented according to licensing terms, features advanced protocol security, and allows users to access authentication, authorization, integrity, and confidentiality. 

How does it work?

The OPC UA framework supports the client-server and publish-subscribe (PubSub) messaging patterns. In the client-server model, a client application sends a request to a server application, which exposes data, responding to the matching request. On the other hand, the PubSub model enables a server to publish data on the network while a subscribed client can access this data. 

By employing the OPC UA standard, it is possible to find servers on local PCs and networks, read and write data based on access permissions, monitor information, and report changes in values as well as notify events by a client’s criteria. A client can easily discover data thanks to its hierarchical representation (the address space principle) and run programs by following server-defined methods.