Reading and Writing Data

Reading Attributes

Reading attributes is done with the Read method.

Read parameters

NodesToRead		Array of nodes and attributes to read
	NodeId	NodeId	The identifier of a node
	AttributeId	uint32	Node Attribute

Read Example

local Server_ServerStatus_CurrentTime = "i=2258"

-- Reading server's current time and product version.
local nodes = {
  NodesToRead = {
    {
      NodeId = Server_ServerStatus_CurrentTime,
      AttributeId = ua.Types.AttributeId.Value
    },
    {
      NodeId = Server_ServerStatus_BuildInfo_SoftwareVersion,
      AttributeId = ua.Types.AttributeId.Value
    },
  }
}

local response = services:read(nodes)
for i,result = response.Results do
  if result.StatusCode == s.Good then
    print(string.format("%s = %s", nodes.NodesToRead[i].NodeId, result.Value.String))
  else
    print(string.format("Reading value '%s' failed: 0x%X", nodes.NodesToRead[i].NodeId, code))
  end
end

Writing Attributes

Changing the values of attributes is done with the Write method.

Write Parameters

NodesToWrite		Array of nodes and attributes to write
	NodeId	NodeId	The identifier of a node
	AttributeId	uint32	Node Attribute
	Value	DataValue	New value of the attribute

Write example

local Server_ServerStatus_StartTime = "i=2257"

local nodes = {
    NodesToWrite = {
      {
        NodeId = ua.NodeIds.Server_ServerStatus_StartTime,
        AttributeId = AttributeId.Value,
        Value = {   -- DataValue
          Value = { -- Variant
            DateTime = 0.0
          }
        }
      }
    }
  }

local response = svc:write(nodes)
if response.Results[1] ~= ua.StatusCode.Good then
  print(string.format("Changing attribute value failed: 0x%X", response.Results[1]))
  return
end

Node Attribute

Every node in the address space is represented by a set of attributes.

Base node attribute numbers

Number	Attribute name	Data type
1	NodeId	nodeID
2	NodeClass	uint32
3	BrowseName	qualifiedName
4	DisplayName	localizedText
5	Description	localizedText
6	WriteMask	uint32
7	UserWriteMask	uint32
24	RolePermissions	structure (TBD)
25	UserRolePermissions	structure (TBD)
26	AccessRestrictions	uint16

Object node attribute numbers

Number	Attribute name	Data type
	Base attributes
12	EventNotifier	byte

Object Type node attribute numbers

Number	Attribute name	Data type
	Base attributes
8	IsAbstract	boolean

Variable node attribute numbers

Number	Attribute name	Data type
	Base attributes
13	Value	DataValue
14	DataType	NodeID
15	Rank	int32
16	ArrayDimensions	int32[]
17	AccessLevel	byte
18	UserAccessLevel	byte
19	MinimumSamplingInterval	double
20	Historizing	boolean
27	AccessLevelEx	uint32

Variable Type node attribute numbers

Number	Attribute name	Data type
	Base attributes
8	IsAbstract	boolean
13	Value	DataValue
14	DataType	NodeID
15	Rank	int32
16	ArrayDimensions	int32[]

Reference Type node attribute numbers

Number	Attribute name	Data type
	Base attributes
8	IsAbstract	boolean
9	Symmetric	boolean
10	InverseName	localizedText

Data Type node attribute numbers

Number	Attribute name	Data type
	Base attributes
8	IsAbstract	boolean
23	DataTypeDefinition	nodeID

Method node attribute numbers

Number	Attribute name	Data type
	Base attributes
21	Executable	boolean
22	UserExecutable	boolean

View node attribute numbers

Number	Attribute name	Data type
	Base attributes
11	ContainsNoLoops	boolean
12	EventNotifier	byte

List of all attribute numbers

Number	Attribute name	Data type
1	NodeId	nodeID
2	NodeClass	uint32
3	BrowseName	qualifiedName
4	DisplayName	localizedText
5	Description	localizedText
6	WriteMask	uint32
7	UserWriteMask	uint32
8	IsAbstract	boolean
9	Symmetric	boolean
10	InverseName	localizedText
11	ContainsNoLoops	boolean
12	EventNotifier	byte
13	Value	DataValue
14	DataType	NodeID
15	Rank	int32
16	ArrayDimensions	int32[]
17	AccessLevel	byte
18	UserAccessLevel	byte
19	MinimumSamplingInterval	double
20	Historizing	boolean
21	Executable	boolean
22	UserExecutable	boolean
23	DataTypeDefinition	nodeID
24	RolePermissions	structure (TBD)
25	UserRolePermissions	structure (TBD)
26	AccessRestrictions	uint16
27	AccessLevelEx	uint32