OPC UA Server

This page describes how the Connectware can act as an OPC UA server. The Connectware can also act as a OPC UA client.

To run an OPC UA server, the commissioning file must contain a server resource of type Cybus::Server::Opcua. This will start an OPC UA server that can be accessed by OPC UA clients. From the OPC UA client, this server is reachable by the following address:

opc.tcp://<connectwareHost>:4841<resourcePath>

The OPC UA server provided by the Connectware uses the non-standard port number 4841 (whereas standard OPC UA uses port 4840) in order to avoid port number collisions on computers where another OPC UA server is already running. Also note: The Connectware can run exactly one instance of an OPC UA server, not multiple instances.

If your Connectware instance is running on a system that is reachable by a DNS hostname, this hostname must be specified in the hostname property, so that the server is reachable from outside of the Connectware docker network. The value localhost is not valid in this case, as localhost refers to the local Docker container but not the host itself, which means this name is not reachable from other containers or the host system.

Additionally, the property resourcePath is important when when connecting to the OPC UA server. This property defines the prefix of the connection string and defaults to the value /UA/CybusOpcuaServer. Please note that this string has to be added to the URL when connecting from a client to the OPC UA Server. Otherwise the client might not be able to connect successfully.

The server configuration is specified by the properties of the server resource. The actual data points (nodes in OPC UA) are specified by defining resources of type Cybus::Node::Opcua, one resource for each node. The nodes are structured in a tree-like hierarchy. There must be exactly one root node, which has its parent property set as a reference to the server object. All other nodes reference either the root node or other intermediate nodes as parent, forming a tree of nodes on the OPC UA Server.

Nodes can be defined within the same service as the OPC UA server, or also in other services using inter-service referencing using the service-id. It is thus possible to add or remove nodes while the OPC UA server is running, by adding more service commissioning files.

Custom Server Properties

Custom Node Properties

Example Commissioning File

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opcua-server-example.yml

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---
description: >

    This is a fixture showing server resource functionality

metadata:
    name: OPC UA Server example
    version: 1.0.0
    icon: https://www.cybus.io/wp-content/uploads/2017/10/for-whom1.svg
    provider: cybus
    homepage: https://www.cybus.io

parameters:
    influxPort:
        type: integer
        default: 8086
        title: Influx Database Port

    retentionTime:
        type: integer
        default: 356
        title: Retention Time

definitions:
    databaseName: opcuaHistory

resources:
    influxdb:
        type: Cybus::Container
        properties:
            image: influxdb:1.8-alpine
            ports:
                - !sub '${influxPort}:8086/tcp'
            volumes:
                - !sub '${influxdbVolume}:/var/lib/influxdb'
            environment:
                INFLUXDB_DB: !ref databaseName
                INFLUXDB_HTTP_FLUX_ENABLED: true

    influxdbVolume:
        type: Cybus::Volume

    opcuaServer:
        type: Cybus::Server::Opcua
        properties:
            database:
                host: 172.17.0.1
                name: !ref databaseName
                retention: !ref retentionTime
            allowAnonymous: false
            certificateFile: /connectware_certs/cybus_server.crt
            privateKeyFile: /connectware_certs/cybus_server.key

    parentNodeRoot:
        type: Cybus::Node::Opcua
        properties:
            browseName: parentNodeRoot
            nodeId: ns=1;s=parentNodeRoot
            parent: !ref opcuaServer
            nodeType: Object

    parentNode1:
        type: Cybus::Node::Opcua
        properties:
            browseName: parentNode1
            nodeId: ns=1;s=parentNode1
            parent: !ref parentNodeRoot
            nodeType: Object

    parentNode2a:
        type: Cybus::Node::Opcua
        properties:
            browseName: parentNode2a
            nodeId: ns=1;s=parentNode2a
            parent: !ref parentNode1
            nodeType: Object

    parentNode2b:
        type: Cybus::Node::Opcua
        properties:
            browseName: parentNode2b
            nodeId: ns=1;s=parentNode2b
            parent: !ref parentNode1
            nodeType: Object

    dataNodeRoot1:
        type: Cybus::Node::Opcua
        properties:
            browseName: dataNodeRoot1
            nodeId: ns=1;s=dataNodeRoot1
            parent: !ref parentNodeRoot
            nodeType: Variable
            operation: serverProvides
            dataType: Boolean

    dataNodeRoot2:
        type: Cybus::Node::Opcua
        properties:
            browseName: dataNodeRoot2
            nodeId: ns=1;s=dataNodeRoot2
            parent: !ref parentNodeRoot
            nodeType: Variable
            operation: serverReceives
            dataType: DateTime

    dataNodeRoot3:
        type: Cybus::Node::Opcua
        properties:
            browseName: dataNodeRoot3
            nodeId: ns=1;s=dataNodeRoot3
            parent: !ref parentNodeRoot
            nodeType: Variable
            initialValue: 42.0
            operation: serverProvidesAndReceives
            dataType: Float
            historize: true

    dataNode1:
        type: Cybus::Node::Opcua
        properties:
            browseName: dataNode1
            nodeId: ns=1;s=dataNode1
            parent: !ref parentNode1
            nodeType: Variable
            operation: serverReceives
            dataType: Int32

    dataNode2a:
        type: Cybus::Node::Opcua
        properties:
            browseName: dataNode2a
            nodeId: ns=1;s=dataNode2a
            parent: !ref parentNode2a
            nodeType: Variable
            operation: serverProvides
            dataType: Double
            historize: true

    dataNode2b:
        type: Cybus::Node::Opcua
        properties:
            browseName: dataNode2b
            nodeId: ns=1;s=dataNode2b
            parent: !ref parentNode2b
            nodeType: Variable
            operation: serverProvides
            dataType: String

    mapping:
        type: Cybus::Mapping
        properties:
            mappings:
                - publish:
                      topic: my/opcuaData/dataNode1
                  subscribe:
                      endpoint: !ref dataNode1

                - publish:
                      endpoint: !ref dataNode2a
                  subscribe:
                      topic: my/opcuaData/dataNode2a

Output Format

If the server receives data from an external OPC UA client, the output on the internal MQTT broker will be provided as JSON object:

{ 'timestamp': '<unix timestamp in ms>', 'value': 'value' }

Input Format

If the server should provide data to an external OPC UA client, the message on the internal MQTT broker must be published in this format:

{ 'value': '<value>' }

Note: If 64-bit integers are being used (which are unsupported in JSON, but are supported in Javascript by the BigInt class), the value must be given as a string that contains the decimal number.