AVEVA™ Adapter for OPC UA

Data source discovery

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Data source discovery

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Last UpdatedJul 23, 2025
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A discovery against the data source of an OPC UA adapter allows you to specify the optional query parameter. The discovery query limits the type (data items or event types) and number of data objects to browse.

Note: Only one discovery at a time is supported.

Query string

The string of the query parameter must contain string items in the following form. Both parameters, RootNodeIds and DiscoveryType, are case sensitive (e.g., rootNodeIds or discoveryType will not be recognized).

RootNodeIds=<nodeId>&DiscoveryType=<Type Value>

String item	Required	Description
RootNodeIds	Optional	The location of the node Ids where the adapter initiates the browse operation. Note: To specify multiple node IDs in the query, separate the node IDs with a comma. If RootNodeIds is not specified, the adapter initiates browse operation from the object folder.
DiscoveryType	Optional	Enumeration value to specify whether discovery should return data items, or event types, or both. DiscoveryType has three allowed, case insensitive values: Data - Only data items display in the discovery results. This is the default behavior. Events - Only event types display in the discovery results. DataAndEvents - Both event type and data item display in the discovery results. Note: If you specify Events, the discovery only returns event types, regardless of whether you include other data item query parameters.

String item

Required

Description

RootNodeIds

Optional

The location of the node Ids where the adapter initiates the browse operation.

Note: To specify multiple node IDs in the query, separate the node IDs with a comma. If RootNodeIds is not specified, the adapter initiates browse operation from the object folder.

DiscoveryType

Optional

Enumeration value to specify whether discovery should return data items, or event types, or both.

DiscoveryType has three allowed, case insensitive values:

Data - Only data items display in the discovery results. This is the default behavior.
Events - Only event types display in the discovery results.
DataAndEvents - Both event type and data item display in the discovery results.

Note: If you specify Events, the discovery only returns event types, regardless of whether you include other data item query parameters.

Note: A NodeId is a unique identification on the OPC UA server that consists of namespace index and identifier.

Query rules

The following rules apply for specifying the query string:

Both parameters, RootNodeIds and DiscoveryType, are case sensitive.
Multiple comma-separated nodeIds are supported.
The nodeId specified in the query string must be valid.
RootNodeIds= must be followed by a nodeId.
Empty string and all white spaces string is equivalent to no query specified.
White spaces in the RooteNodeIds= section of the query are not supported
When DiscoveryType is set to DataAndEvents, including RootNodeIds limits the scope of data items returned to the nodeIds specified. In addition, Event Types available on the server are included in the discovery results.
When DiscoveryType is set to Events, specifying RootNodeIds does not have any effect on the discovery results. Only event types are returned and RootNodeIds is ignored.
autoSelect is supported for all query configurations

Note: The data source might contain large amounts of items. Use the RootnodeIds in the query string to browse only items that you need.

AVEVA™ Adapter for OPC UA