Owning Palette: OPC UA Client VIs

Requires: OPC UA Toolkit

Adds nodes to a data subscription to monitor data changes.

Example

monitoring parameters specifies the settings for monitoring data changes.
sampling interval specifies the maximum rate for the OPC UA server to sample its underlying source for data changes. The default is -1, which specifies that the sampling interval is the same as the publishing interval of the subscription.
queue size specifies the size of the queue that stores the data change notification to the subscription. The default is 1.
discard oldest specifies whether to discard the oldest element in the queue. The default is TRUE, which specifies to discard the oldest element in the queue.
data change filter specifies values to filter data changes.
trigger specifies the conditions under which LabVIEW reports a data change notification.
0StatusLabVIEW reports a notification only when the status code associated with the value changes.
1StatusValue (default)LabVIEW reports a notification when the value or the status code associated with the value changes.
2StatusValueTimestampLabVIEW reports a notification when the status code associated with the value, the value, or the source timestamp changes. If you specify the deadband filter, this option has the same behavior as StatusValue.
deadband type defines the type of the deadband. Deadband is the range for value changes that do not trigger a data change notification.
0None (default)
1Absolute
2Percent
deadband value specifies the value of the deadband. The default is 0. For the Absolute deadband type, deadband value is the absolute change in a data value that causes LabVIEW to generate a notification. For the Percent deadband type, deadband value is the percentage of the EU range and only applies to analog items.
OPC UA client refnum in specifies the reference for the OPC UA client.
subscription ID in specifies the ID of the subscription.
node IDs specifies the IDs of the nodes. The format of the node ID is ns=<namespace index>;<identifier type>=<identifier>. A node ID contains the following components:
  • namespace index is a base 10 number that indicates the namespace of the node ID.
    Note If namespace index is 0, the format of the node ID can be <identifier type>=<identifier>. The namespace index for a node that you created with the OPC UA Toolkit is 2.
  • identifier type represents the type of the identifier and has the following values:
    ValueIdentifier Type
    iNumeric
    sString
    gGUID
    bOpaque
  • identifier is a string value that represents the name of the identifier.
The format of the node ID can also be ns=<namespace index>;<identifier type>=<identifier>@<index>:<index>. For example, ns=2;s=Folder.Array@1:2. This format only applies to the array data type and allows you to read a single element or a range of elements of an array. You cannot use @ in a node name. For backwards compatibility, node IDs also accepts node paths as input for OPC UA servers only. You can regard the node path as the string type identifier of the node ID. For example, a node path can be Device.folder.item.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
timeout specifies the maximum time, in milliseconds, that this VI waits to get a response from the OPC UA server. The default is 5000.
OPC UA client refnum out returns the reference for the OPC UA client.
status returns the status code.
error out contains error information. This output provides standard error out functionality.
service status returns the status of an OPC UA service call. OPC UA services contain parameters that are conveyed between an OPC UA client and an OPC UA server.

Example

Refer to the OPC UA Demo.lvproj in the labview\examples\Data Communication\OPCUA directory for an example of using the Add Monitored Data Nodes VI.