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:


Note: 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

port (integer)

Port of the listening socket

Default: 4841

Example: 4841

maxSessions (integer)

Max Sessions allowed by user

Default: 20

Example: 1000

maxConnections (integer)

Max Connections allowed for a single endpoint to prevent DDoS attacks

Default: 20

Example: 1000

resourcePath (string)

Resource Path of the OPC Server. This must be added to the OPC UA connection URN of the client

Default: "/UA/CybusOpcuaServer"

Examples: "/UA/CybusOpcuaServer", "/My/IndividualName"

alternateHostname (string)

This setting is deprecated, has been renamed into ‘hostname’, and will be removed in a future release

Examples: "", "my.connectware-host.company.com"

hostname (string)

The hostname by which the Connectware with the OPC UA server will be reachable on the system. This can be either an IP address or a DNS name.

Examples: "", "my.connectware-host.company.com"

applicationUri (string)

The application URI is used to define the namespace name of the Connectware defined NodeIds

Default: "urn:cybus:opcua:server:1"

Example: "urn:cybus:opcua:server:1"

allowAnonymous (boolean)

If true, usage of anonymous access token is allowed. In that case, OPC UA clients are allowed to connect without any authentication. Note: This is a high security risk and must not be used in production deployments.

Default: false

Example: true

certificateFile (string)

Absolute path to the server certificate file

Default: "/connectware_certs/cybus_server.crt"

Example: "/connectware_certs/cybus_server.crt"

privateKeyFile (string)

Absolute path to the server private key file

Default: "/connectware_certs/cybus_server.key"

Example: "/connectware_certs/cybus_server.key"

securityPolicies (array)

Defines the list of OPC UA securityPolicies that will be available on the server. Note: The policy “None” is a high security risk and must not be used in production deployments.

The object is an array with all elements of the type string.

Each element of the array must be one of the following enum values:

  • Basic256Sha256

  • None



Example: "[\"Basic256Sha256\", \"None\"]"

nodesetFiles (array)

Predefined Nodeset files to load on startup

The object is an array with all elements of the type string.

Each element of the array must be one of the following enum values:

  • standard

  • di

  • ia

  • machinery

  • machineTool

  • packML

  • robotics

  • Opc.Ua.PlasticsRubber.GeneralTypes.NodeSet2.xml

  • Opc.Ua.PlasticsRubber.IMM2MES.NodeSet2.xml

  • Opc.Ua.PLCopen.NodeSet2.xml

securityModes (array)

Defines the list of OPC UA security modes which an OPC client can use to establish a connection to the Cybus OPC UA server

The object is an array with all elements of the type string.

Each element of the array must be one of the following enum values:

  • Invalid

  • None

  • Sign

  • SignAndEncrypt



Example: "[\"None\", \"SignAndEncrypt\"]"

database (object)

Definition of the database for historical access of the data. If this property exists, historical access is enabled, otherwise it is not enabled.

Properties of the database object:

type (string, enum)

Type of the history database

This element must be one of the following enum values:

  • influx

Default: "influx"

Example: "influx"

host (string)

Database Host

Example: ""

port (integer)

Port of the database server

Default: 8086

Example: 8086

name (string)

Database Name

Example: "opcuaHistory"

retention (integer)

Data older than the specified number of days will be automatically discarded

Example: 356

Custom Node Properties

browseName (string, required)

The browse name (not path) of this node

Examples: "temperature1", "pressure2"

nodeId (string)

The specific node id of this node

Example: "ns=1;s=spindleSpeed"

nodeType (string, enum, required)

The node type: Whether this node is a variable or an object.

This element must be one of the following enum values:

  • Object

  • Variable

historize (boolean)

Whether to accumulate an historian for this node

Default: false

interpolation (string, enum)

The displayed interpolation mode

This element must be one of the following enum values:

  • stepped

  • sloped

Default: "sloped"

maxTimeInterval (integer)

Specifies the maximum interval between data points in the history repository regardless of their value change [in milliseconds]

Default: 10000

Example: 1000

minTimeInterval (integer)

Specifies the minimum interval between data points in the history repository regardless of their value change [in milliseconds]

Default: 500

Example: 100

dataType (string)

The data type of this node. This can be either an OPC UA base type (see example values), or a node ID which references a data type node.

Examples: "Boolean", "Byte", "ByteString", "DataValue", "DateTime", "DiagnosticInfo", "Double", "ExpandedNodeId", "ExtensionObject", "Float", "Guid", "Int16", "Int32", "Int64", "LocalizedText", "NodeId", "Null", "QualifiedName", "SByte", "StatusCode", "String", "UInt16", "UInt32", "UInt64", "Variant", "XmlElement"

serializeDataType (string, enum)

For nodes where the data type is not an OPC UA base type but a node reference, the data type for serialization of values sometimes needs to be specified separately here. This must be a basic OPC UA data type.

This element must be one of the following enum values:

  • Boolean

  • Byte

  • ByteString

  • DataValue

  • DateTime

  • DiagnosticInfo

  • Double

  • ExpandedNodeId

  • ExtensionObject

  • Float

  • Guid

  • Int16

  • Int32

  • Int64

  • LocalizedText

  • NodeId

  • Null

  • QualifiedName

  • SByte

  • StatusCode

  • String

  • UInt16

  • UInt32

  • UInt64

  • Variant

  • XmlElement

valueRank (integer, enum)

The rank of the transported data, default is scalar (-1), use 1 for array of scalars

This element must be one of the following enum values:

  • -3

  • -2

  • -1

  • 0

  • 1

  • 2

Default: -1

arrayDimensions (array)

For nodes that represent an array or a multi-dimensional array (e.g. a matrix), this array value specifies the size in each of the dimensions.

The object is an array with all elements of the type number.

Example: [6,4]

Example Commissioning File

Download: opcua-server-example.yml

  2description: >
  4  This is a fixture showing server resource functionality
  8  name: OPC UA Server example
  9  version: 1.0.0
 10  icon: https://www.cybus.io/wp-content/uploads/2017/10/for-whom1.svg
 11  provider: cybus
 12  homepage: https://www.cybus.io
 16  influxPort:
 17    type: integer
 18    default: 8086
 19    title: Influx Database Port
 21  retentionTime:
 22    type: integer
 23    default: 356
 24    title: Retention Time
 28  databaseName: opcuaHistory
 32  influxdb:
 33    type: Cybus::Container
 34    properties:
 35      image: influxdb:1.8-alpine
 36      ports:
 37        - !sub '${influxPort}:8086/tcp'
 38      volumes:
 39        - !sub '${influxdbVolume}:/var/lib/influxdb'
 40      environment:
 41        INFLUXDB_DB: !ref databaseName
 44  influxdbVolume:
 45    type: Cybus::Volume
 47  opcuaServer:
 48    type: Cybus::Server::Opcua
 49    properties:
 50      database:
 51        host:
 52        name: !ref databaseName
 53        retention: !ref retentionTime
 54      allowAnonymous: false
 55      certificateFile: /connectware_certs/cybus_server.crt
 56      privateKeyFile: /connectware_certs/cybus_server.key
 58  parentNodeRoot:
 59    type: Cybus::Node::Opcua
 60    properties:
 61      browseName: parentNodeRoot
 62      nodeId: ns=1;s=parentNodeRoot
 63      parent: !ref opcuaServer
 64      nodeType: Object
 66  parentNode1:
 67    type: Cybus::Node::Opcua
 68    properties:
 69      browseName: parentNode1
 70      nodeId: ns=1;s=parentNode1
 71      parent: !ref parentNodeRoot
 72      nodeType: Object
 74  parentNode2a:
 75    type: Cybus::Node::Opcua
 76    properties:
 77      browseName: parentNode2a
 78      nodeId: ns=1;s=parentNode2a
 79      parent: !ref parentNode1
 80      nodeType: Object
 82  parentNode2b:
 83    type: Cybus::Node::Opcua
 84    properties:
 85      browseName: parentNode2b
 86      nodeId: ns=1;s=parentNode2b
 87      parent: !ref parentNode1
 88      nodeType: Object
 90  dataNodeRoot1:
 91    type: Cybus::Node::Opcua
 92    properties:
 93      browseName: dataNodeRoot1
 94      nodeId: ns=1;s=dataNodeRoot1
 95      parent: !ref parentNodeRoot
 96      nodeType: Variable
 97      operation: serverProvides
 98      dataType: Boolean
100  dataNodeRoot2:
101    type: Cybus::Node::Opcua
102    properties:
103      browseName: dataNodeRoot2
104      nodeId: ns=1;s=dataNodeRoot2
105      parent: !ref parentNodeRoot
106      nodeType: Variable
107      operation: serverReceives
108      dataType: DateTime
110  dataNodeRoot3:
111    type: Cybus::Node::Opcua
112    properties:
113      browseName: dataNodeRoot3
114      nodeId: ns=1;s=dataNodeRoot3
115      parent: !ref parentNodeRoot
116      nodeType: Variable
117      initialValue: 42.0
118      operation: serverProvidesAndReceives
119      dataType: Float
120      historize: true
122  dataNode1:
123    type: Cybus::Node::Opcua
124    properties:
125      browseName: dataNode1
126      nodeId: ns=1;s=dataNode1
127      parent: !ref parentNode1
128      nodeType: Variable
129      operation: serverReceives
130      dataType: Int32
132  dataNode2a:
133    type: Cybus::Node::Opcua
134    properties:
135      browseName: dataNode2a
136      nodeId: ns=1;s=dataNode2a
137      parent: !ref parentNode2a
138      nodeType: Variable
139      operation: serverProvides
140      dataType: Double
141      historize: true
143  dataNode2b:
144    type: Cybus::Node::Opcua
145    properties:
146      browseName: dataNode2b
147      nodeId: ns=1;s=dataNode2b
148      parent: !ref parentNode2b
149      nodeType: Variable
150      operation: serverProvides
151      dataType: String
153  mapping:
154    type: Cybus::Mapping
155    properties:
156      mappings:
157        - publish:
158            topic: my/opcuaData/dataNode1
159          subscribe:
160            endpoint: !ref dataNode1
162        - publish:
163            endpoint: !ref dataNode2a
164          subscribe:
165            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.