OPC UA - Server Discovery
It is possible to define either a URL or a URI in the configuration panel for OPC UA servers. Using URIs allows to configure and use OPC UA servers independently from host name and IP address. In this case the given URI is used to determine the corresponding URL by a Local Discovery Server (LDS). Therefore, no further changes to the WinCC OA configuration are necessary if you want to run the OPC UA server on another host. You only have to register the OPC UA server at the respective LDS.
Registering a WinCC OA OPC UA server
To register a WinCC OA OPC UA server at a Local Discovery Server, the config entry discoveryServer must be set in the respective section [opcuasrv].
Manual server discovery
Figure: OPC UA configuration panel
Server URL/URI
Enter the URL to the server (TCP/IP address and port number). The server URL can be entered directly or selected via the OPC UA Discovery panel. Click the "..." button to open the panel.
Enter the IP address of the LDS in the Discovery Server URL text field and click the Discover button to get a list of servers which are registered at this LDS.
All available servers including their supported endpoints are listed. If you select an endpoint and confirm with the OK button, the server URL as well as strategy and message mode settings are automatically applied.
Automatic server discovery
Figure: OPC UA configuration panel
Server URL/URI
Define the URI which shall be converted to the appropriate URL by a Local Discovery Server. The URI of a server must be entered in the Server URL/URI text field. You have to define a Local Discovery Server for the connection to convert the URI into a URL. Therefor, go to System management > Driver OPC > OPC UA Local Discovery Server to open the following panel:
This panel allows to define the Local Discovery Servers for resolving URIs. It is possible to specify the LDS for a single server connection or the client (thus, all related server connections). If the client tries to resolve a server URI, it browses the URI in all servers registered at the specified Local Discovery Servers to determine the corresponding URL. At first, the server connection specific LDS entries are browsed. If the URI cannot be found, the client related LDS entries are browsed.
Server URIs are only resolved when the connection is established. Therefore changes to the URI - URL mapping of the LDS are only applied after you reestablish the connection to a server. Without LDS the URI cannot be converted and it is not possible to connect to the server.
