Extra application-specific properties (optional).
Identifies the OPC UA data item to be monitored by its browse path (optional).
This property should be used if the NodeID of the data source is not
known beforehand. If the NodeId is known, use the nodeIdentifier
property instead. Note that exactly one of both properties must be
specified.
The browse path consists of a root node, e.g. "RootFolder", and a
relative path of BrowseNames to the target item, e.g.
"/Objects/Server.ServerStatus.BuildInfo". Note that the final browse
name in the path must specify the item to be monitored, it must not be
omitted (i.e. no wildcard operation is allowed). A specification of the
relative path BNF can be found
here.
Note that in addition to this specification, a browse name within a
relative path can also be qualified with a namespace URI instead of a
namespace index, in the format [<namespace-uri>]:<name>. For example,
[urn:MyOPCUA-Server-default]:MyDevice instead of 1:MyDevice. We
recommend to always use namespace URIs so that browse paths can be
persisted and resolved across OPC UA sessions.
A coercion function that coerces a given OPC UA data value to a value used by application or vice versa (optional).
If not specified, no coercion takes place and the original value is used.
The coercion function is applied in all OPC UA related operations, i.e. when reading, writing, and monitoring OPC UA items. If the coercion function throws an error when invoked, the related operation is not executed and the error is signalled to the invoker of the operation.
The forReading parameter determines whether coercion is invoked for
reading/monitoring an OPC UA value or for writing the value of an OPC UA
item.
The OPC UA data type used for writing the value of an OPC UA variable
(optional). Only used by writing methods of OpcuaConnector.
Monitoring parameters influence which information is delivered to the client (optional). Main monitoring parameters are the data change filter, size of monitored item queue, and sampling interval (in milliseconds; it is the fastest rate at which the monitored items should be accessed and evaluated).
Determines whether to discard the oldest value or the latest value from the monitored item queue in case the queue overflows (optional).
If not specified, the value defaults to true. If queue size is set to 1, the discard policy is ignored.
An optional data change filter is used when you are only interested
in certain kinds of changes in the monitored item, or need to reduce
the amount of incoming notifications by specifying a deadband. The
data change filter defines the conditions under which a data change
notification should be reported and, optionally, a range or band for
value changes where no data change notification is generated
(deadband). See type
DataChangeFilter
of node-opcua-client package.
If not specified, no data change filter is set.
For example, to set a data change filter with a deadband trigger:
import { DataChangeFilter, DataChangeTrigger, DeadbandType } from "node-opcua-client";
filter: new DataChangeFilter({
trigger: DataChangeTrigger.StatusValue,
deadbandType: DeadbandType.Absolute,
deadbandValue: 0.1
})The queue size for a monitored item, i.e. the maximum number of data
samples which can be queued on the server. When the data gets
delivered to the client (publish) the queue gets emptied. Each queue
has a discard policy in case an overflow occurs, see property
discardOldest.
Value must be a UInt32. If not specified, the value defaults to 1.
The interval that defines the fastest rate at which MonitoredItem(s) should be accessed and evaluated (optional, for monitored items only).
This interval is defined in milliseconds. The default is -1, which specifies that the sampling interval is the same as the publishing interval of the subscription.
Identifies the OPC UA item to be monitored by its fully qualified NodeId (optional).
This property should be used if the NodeId of the data item is known
beforehand. If only the browse path of the data item is known, use the
browsePath property instead. Note that exactly one of both properties
must be specified.
Determines whether the OPC UA data item should be monitored (optional).
If not specified, the item is not monitored by default.
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Defines characteristics of an OPC UA data source, including its NodeId or browse path, and optional characteristics for monitoring and data value coercion.