The Local Discovery Server (LDS) is an OPC UA Server that implements the Discovery Service Set defined in OPC 10000-4. If an LDS is installed on a machine, it shall use one or more of the well-known addresses defined in Table 80.

Table 80 – Well known addresses for Local Discovery Servers

Transport Mapping	URL	Notes
OPC UA TCP	opc.tcp://localhost:4840/UADiscovery
OPC UA WebSockets	opc.wss://localhost:443/UADiscovery
OPC UA HTTPS	opc.https://localhost:443/UADiscovery

OPC UA applications that make use of the LDS shall allow administrators to change the well-known addresses used within a system.

The Endpoint used by Servers to register with the LDS shall be the base address with the path “/registration” appended to it (e.g. http://localhost/UADiscovery/registration). OPC UA Servers shall allow administrators to configure the address to use for registration.

Each OPC UA Server application implements the Discovery Service Set. If the OPC UA Server requires a different address for this Endpoint, it shall create the address by appending the path “/discovery” to its base address.