A vendor that is developing an OPC UA application, shall review the list of available Profiles. From this list the vendor shall select the Profilesthat include the functionality required by the application. Conformance to a single Profilemay not yield a complete application. In most cases multiple Profilesare needed to yield a useful application. All UA applications shall support at least one Application Profile.

For example an HMI Clientapplication may choose to support the Minimum UA Client 2022 Profile, the “Data Access Client Facet”, the “DataChange Subscriber Client Facet” and the “Attribute Write Client Facet”. This list of Profileswould allow the Clientto communicate with an OPC UA Serverusing UA-TCP/UA Security/UA Binary. It would be able to subscribe for data, write to data and would support the DA data model.

Clientsshould take into account the types of Serversand Server Profilesthat they are targeted to support. Some Serversmight not support Subscriptionsand Clientsshould be able to fall back to the Read Service.

A special case is a generic Clientthat is designed to communicate with a large number of Serversand therefore able to perform a broad range of functionality. ”Standard UA Client Profile”has been defined for this kind of Clients.

Many Clients, however, will be specialized and do not need all of the functionality in the ”Standard UA Client Profile”and thus would only support the limited set of functionality they require. A trend Client, for example, would only need functionality to subscribe to or read data.