This plugin is based on the S2OPC open source library.

OPC UA server protocol stack configuration

Connection configuration

This section provides the connection-level configuration details of an OPC UA server. 

Attributes definition

Configuration JSON structure

{
   "transport_layer":{
      "url":"opc.tcp://localhost:4841/OPCUA/s2opc",
      "appUri":"urn:S2OPC:localhost",
      "productUri":"urn:S2OPC:localhost",
      "appDescription":"Application description",
      "localeId":"en-US",
      "namespaces":[ "urn:S2OPC:localhost" ],
      "policies":[
         {
            "securityMode":"None",
            "securityPolicy":"None",
            "userPolicies":[
               "anonymous"
            ]
         },
         {
            "securityMode":"SignAndEncrypt",
            "securityPolicy":"Basic256Sha256",
            "userPolicies":[
               "username_Basic256Sha256",
               "username_None"
            ]
         }
      ],
      "users":{ "user":"password", "user2":"xGt4sdE3Z+" },
      "certificates":{
         "serverCertPath":"server_2k_cert.der",
         "serverKeyPath":"server_2k_key.pem",
         "trusted_root":[ "cacert.der" ],
         "trusted_intermediate":[],
         "revoked":["cacrl.der"],
         "untrusted_root":[],
         "untrusted_intermediate":[],
         "issued":[]
      }
   }
}

OPC UA server endpoint interface

Connection

A client requires knowledge of parameters provided in previous section to establish a secured channel with the server:

• Endpoint URL
• Server certificate (It is the responsibility of the client to ensure it is connecting to the expected server)
• User login/password, if applicable.

Endpoint

This section provides the user-level configuration details of an OPC UA server, once a client-server secured connection is established.

The endpoint (see "transport_layer.url") is an OPC UA interface and provides several means of use by a client (Browse, Read, Write, Subscribe). The following items allow any connected client to access directly all server data without prior use of browsing, provided that it has knowledge of the PIVOT object it needs and there related types.

Interface specification:

With <PIVOT_ID> as provided in exchanged_data.datapoints[].pivot_id section configuration.

Notes:

• All read-only variables have a OpcUa_BadWaitingForInitialData quality (0x80320000) initial value until a valid value is received from FledgePower.
• All non-mandatory values will be set automatically by the server if not received from a south device.
• If a mandatory value is missing, then the whole PIVOT object is not updated.
• As a standard OPC UA server, all functional data are organized under the Root.Objects  node of namespace 0 ( nodeId = i=85).
• All data are stored under the namespace 1. Its URI is configured in protocol "namespaces" parameter.

Value content and metadata

PIVOT timestamp

The ns=1;s=<PIVOT_ID>/Value variable contains the pivot timestamp value (t.FractionOfSecond + t.SecondSinceEpoch) is converted to OPC-UA timestamp (Unit=  number of 100 nanosecond since Jan 1st,1600).

The timestamp is not optional in OPCUA. Thus, in case the timestamp were not provided by south layers, the OPC UA north plugin will set the timestamp to 0.

PIVOT value validity

The ns=1;s=<PIVOT_ID>/Value variable contains the pivot value <Root<.<type>.q.validity field. It is represented as the OPC UA Quality of the variable, using the following conversion:

PIVOT variant value

The base type of the value itself is static and depends on the configuration provide in  "exchanged_data" section.