This Attribute specifies the length of each dimension for an array value.
valueRank
Attribute.valueRank
<=0.example
For example, if a Variable is defined by the following javascript array with 346 Int32 elements:
const myArray = new Array(346).fill(0);
then:
DataType
would point to an Int32
valueRank
has the value 1 and,arrayDimensions
is an array with one entry having the value 346.{
dataType: "Int32",
valueRank: 1,
arrayDimensions: [346]
}
Note: the maximum length of an array transferred on the wire is 2147483647 (max Int32) and a multidimensional array is encoded as a one dimensional array.
The historizing
attribute indicates whether the server is actively collecting data for the
history of the variable.
This differs from the accessLevel
Attribute which identifies if the variable has any historical data.
A value of true indicates that the server is actively collecting data.
A value of false indicates the server is not actively collecting data.
Default value is false.
The MinimumSamplingInterval Attribute indicates how 'current' the Value of the Variable will be kept.
It specifies (in milliseconds) how fast the Server can reasonably sample the value for changes (see Part 4 for a detailed description of sampling interval).
A MinimumSamplingInterval of 0 indicates that the Server is to monitor the item continuously.
A MinimumSamplingInterval of -1 means indeterminate.
NodeVersion (Optional) String The NodeVersion Property is used to indicate the version of a Node. The NodeVersion Property is updated each time a Reference is added or deleted to the Node the Property belongs to. Attribute value changes do not cause the NodeVersion to change. Clients may read the NodeVersion Property or subscribe to it to determine when the structure of a Node has changed.
The UserAccessLevel Attribute is used to indicate how the Value of a Variable can be accessed (read/write) and if it contains current or historic data taking user access rights into account.
The AccessLevelType is defined in 8.57.
This Attribute indicates whether the Value Attribute of the Variable is an array and how many dimensions the array has. It may have the following values:
NOTE:
browse the node to extract information requested in browseDescription
find the the references that are strictly of type reference
.
The isForward boolean flag specifies the direction of the references to be looked for.
Forward direction is implied if omitted.
find all the references that are strictly of type reference
.
The isForward boolean flag specifies the direction of the references to be looked for.
Forward direction is implied if omitted.
find all the nodes that are referenced by references strictly of type reference
.
The isForward boolean flag specifies the direction of the references to be looked for.
Forward direction is implied if omitted.
find all the references that are of type reference
or a sub type of reference
, in the
direction specified by browseDirection
find all the nodes that are referenced by references of type reference
or a sub type of reference
, in the
direction specified by browseDirection
return a complete name of this object by pre-pending name of its parent(s) to its own name
get effective accessRestrictions if (inherited is true) and node has no accessRestrictions, then default accessRestriction from namespace is returned if (inherited is false) and node has no accessRestrictions, then AccessRestrictionsFlag.None is returned
the locale of the text to return (e.g. en-EN)
return a array of the objects for which this node is an EventSource nodes = HasEventSource => self
return a array with the event source of this object. self = HasEventSource => nodes
private
returns true if the accessLevel
flag allows the variable to be readable in the specified context.
returns true if the userAccessLevel
flag allows the variable to be readable in the specified context.
returns true if the userAccessLevel
flag allows the variable to be writeable in the specified context.
returns true if the accessLevel
flag allows the variable to be writeable in the specified context.
from OPC.UA.Spec 1.02 part 4 5.10.2.4 StatusCodes Table 51 defines values for the operation level statusCode contained in the DataValue structure of each values element. Common StatusCodes are defined in Table 166.
Read Operation Level Result Codes
Symbolic Id | Description |
---|---|
BadNodeIdInvalid | The syntax of the node id is not valid. |
BadNodeIdUnknown | The node id refers to a node that does not exist in the server address space. |
BadAttributeIdInvalid | BadAttributeIdInvalid The attribute is not supported for the specified node. |
BadIndexRangeInvalid | The syntax of the index range parameter is invalid. |
BadIndexRangeNoData | No data exists within the range of indexes specified. |
BadDataEncodingInvalid | The data encoding is invalid. This result is used if no dataEncoding can be applied because an Attribute other than Value was requested or the DataType of the Value Attribute is not a subtype of the Structure DataType. |
BadDataEncodingUnsupported | The server does not support the requested data encoding for the node. This result is used if a dataEncoding can be applied but the passed data encoding is not known to the Server. |
BadNotReadable | The access level does not allow reading or subscribing to the Node. |
BadUserAccessDenied | User does not have permission to perform the requested operation. (table 165) |
BadSecurityModeInsufficient | The operation is not permitted over the current secure channel. |
BadInsufficientPrivileges | The user does not have enough privileges to perform the requested operation. |
setAccessRestriction
write a variable attribute (callback version)
example
const writeValue = {
attributeId: AttributeIds.Value,
dataValue: new DataValue({
statusCode: StatusCodes.Good,
sourceTimestamp: new Date(),
value: new Variant({ dataType: DataType.Double, value: 3.14 })
}),
nodeId
};
myVariable.writeAttribute(context,writeValue,(err, statusCode) => {
if (err) { console.log("Write has failed"); return; }
console.log("write statusCode = ",statusCode.toString());
});
write a variable attribute (async/await version)
example
try {
const writeValue = {
attributeId: AttributeIds.Value,
dataValue: new DataValue({
statusCode: StatusCodes.Good,
sourceTimestamp: new Date(),
value: new Variant({ dataType: DataType.Double, value: 3.14 })
}),
nodeId
};
const statusCode = await myVariable.writeAttribute(context,writeValue);
} catch(err) {
console.log("Write has failed");
return;
}
console.log("write statusCode = ", statusCode.toString());
Generated using TypeDoc
The AccessLevel Attribute is used to indicate how the Value of a Variable can be accessed (read/write) and if it contains current and/or historic data.
The AccessLevel does not take any user access rights into account, i.e. although the Variable is writable this may be restricted to a certain user / user group.
The {{link:AccessLevelType}}