VariableNode Class Reference

Represents an OPCUA variable node. More...

Inherits BaseNode.

Inherited by FloatNode, IntegerNode, and StringNode.

Public Member Functions
None	deregister_callback (self, cvb.EventCookie event_cookie)
	Deregisters a callback. More...
cvb.EventCookie	register_read_callback (self, Callable[[], None] callback)
	Registers a callback for the read operations on this node. More...
cvb.EventCookie	register_write_callback (self, Callable[[], None] callback)
	Registers a callback for the write operations on this node. More...
Public Member Functions inherited from BaseNode
List[cvb.opcua.NodeID]	browse (self, cvb.opcua.BrowseFilter filter_options)
	Enumerates the child nodes present in the OPCUA server. More...
Union[int, float, str]	get_attribute (self, int attribute_id)
	Gets specific information about this node. More...
cvb.opcua.NodeID	node_id (self)
	Gets the OPCUA node ID of this node. More...
None	set_attribute (self, int attribute_id, Union[int, float, str] value)
	Sets specific information about this node. More...

Properties
	datatype = property
	int: Gets the data type of this node (see cvb.opcua.DataType).
Properties inherited from BaseNode
	access = property
	int: Gets access rights to this node (see cvb.opcua.Access).
	browse_name = property
	str: Gets the browse name of this node.
	connection_status = property
	int: Gets connection status of this node (see cvb.opcua.ConnectionStatus).
	description = property
	str: Gets description of this node.
	display_name = property
	str: Gets the human-readable name of this node.
	node_class = property
	int: Gets OPCUA node class of this node (see cvb.opcua.NodeClass).

Detailed Description

Represents an OPCUA variable node.

It handles the data modeling according to the OPCUA specification. It serves as the basis (shared functionality) for cvb.opcua.StringNode and similar. It will also created/returned if no specific implementation for the given variable node is available. OPCUA nodes are available for different node classes.

Member Function Documentation

deregister_callback()

None deregister_callback	(		self,
		cvb.EventCookie	event_cookie
	)

Deregisters a callback.

The usage of callback for data access is highly recommended. Note that the callback MUST be deregistered, otherwise internal object handles will not be closed.

Parameters

event_cookie : cvb.EventCookie Event cookie of the registered callback.

register_read_callback()

cvb.EventCookie register_read_callback	(		self,
		Callable[[], None]	callback
	)

Registers a callback for the read operations on this node.

The usage of callback for data access is highly recommended. Note that the callback MUST be deregistered, otherwise internal object handles will not be closed.

Parameters

callback : Callable[[], None] Callback to execute.

Returns

cvb.EventCookie Cookie for unregistering the registered callback.

register_write_callback()

cvb.EventCookie register_write_callback	(		self,
		Callable[[], None]	callback
	)

Registers a callback for the write operations on this node.

The usage of callback for data access is highly recommended. Note that the callback MUST be deregistered, otherwise internal object handles will not be closed.

Parameters

callback : Callable[[], None] Callback to execute.

Returns

cvb.EventCookie Cookie for unregistering the registered callback.