TagsOnly mode
- Last UpdatedJun 10, 2025
- 3 minute read
In this mode, users have the option to reference a .csv file with a list of NodeIds and several other optional columns. Only those OPC UA variables, which have their NodeIds listed in the file, will be subscribed for changes and will consequently forward events to the PI System.
This mode is fundamentally different from all the modes described previously where the connector initially browses the whole OPC UA address space and users have the option to select objects that they are interested in. The TagsOnly mode is very explicit and along with listing the NodeIds allows for providing a couple of additional input parameters on a per-NodeId basis.
Note: In this mode, no PI AF hierarchy is created; nevertheless, the discovery of the OPC UA server address space (Discover Data Source Contents button in PI Data Collection Manager) must be initiated. The referenced list of explicit NodeIds, however, makes sure the discovery process will be efficient.
NodeID parameters
|
Parameter |
Required/Optional |
Definition and syntax |
|---|---|---|
|
NodeId |
Required |
The OPC UA variable's NodeId in the following format: ns=NamespaceIndex;IdentifierType=identifier Note: In a TagsOnly .csv file, the connector interprets a comma as a separator or a delimiter. If you need to use a comma with the NodeId, you must use double quotes. For example, "ns=3;s=3513 Example.i.l,x1". |
|
SamplingInterval |
Optional |
A time in milliseconds, which defines the fastest rate at which a given OPC UA variable will be accessed. If not specified the value is taken from the corresponding input under: Advanced Configuration -> OPC UA Subscription Parameters |
|
QueueSize |
Optional |
The requested size of the MonitoredItem queue. If not specified the value is taken from the corresponding input under: Advanced Configuration -> OPC UA Subscription Parameters |
|
MonitoringMode |
Optional |
Determines if an OPC UA variable will be active or inactive. The corresponding OPC UA variable will be included in a subscription, but it won't produce OPC UA value event notifications if the MonitoringMode for the variable is disabled. MonitoringMode may be set to:
|
|
DataChangeTrigger |
Optional |
The type of change that triggers an OPC UA value event notification:
|
|
Deadband |
Optional |
The dead-band. Additional input is specified in the DeadBandType column. Default is 0. |
|
DeadbandType |
Optional |
The DeadbandType can be Absolute, None, or Percent. The value event is triggered if the Abs(last value - new value) > DeadBand. The dead-band type=Percent is only valid for variables having the EURange defined. The Percent mode triggers an OPC UA value event notification of change only if a change is more than the specified percentage of the value range. The default is None. |
In the .csv file, the only mandatory column is NodeId. The simplest example of this file is as follows:
NodeId
ns=5;s=Counter1
If a file with the above content is referenced to the connector, it will only replicate data from the variable having the listed NodeId.
The order of all optional columns is not important. Any optional column can even be omitted and the default will be considered.
Note: The TagsOnly mode is also different when compared with the same mode implemented in PI Connector for OPC UA version 1.x. The main difference is that the CustomStreamId column is not considered. The reason for it is that users have the option to rename PI points through the tag naming feature provided with PI Data Collection Manager.