OPC Item

An item in an OPC UA Server

The OPC Item item type has the following properties:

NameDescriptionIDFlags
DeadbandTypeThe monitoring deadband. Default = None.10550Persisted, Enumerated
DeadbandValueThe value of the monitoring deadband. Ignored when 'Deadband' is 'None'.10560Persisted
DiscardOldestThe discard policy when the queue is full 110530Persisted
ExcludeFromCatchupIf true, this item is excluded from catchup 210600Persisted
MonitoringModeEnable or disable the sampling of a MonitoredItem 310500Persisted, Enumerated
MonitorStateThe state of the monitored item.11030ReadOnly
QueueSizeThe requested size of the "MonitoredItem" queue. Default = 1.10520Persisted
RevisedQueueSizeThe actual queue size that the Server will use.11020ReadOnly
RevisedSamplingIntervalThe actual sampling interval that the Server will use 411010ReadOnly
SamplingIntervalDefines the fastest rate at which the MonitoredItem(s) should be accessed and evaluated 510510Persisted
SrcUaNodeIdUA Node ID in source.5031Persisted
SrcUaNodeId-HAUA Node ID used for reading history 610505Persistd
TriggerThe conditions under which a data change notification should be reported 710540Persisted, Enumerated
Write as server datatypeData type used when writing value to the server 810610Persisted, Expert
1

A boolean parameter. It has the following values:True - the oldest (first) notification in the queue is discarded. The new notification is added to the end of the queue;False - the last notification added to the queue gets replaced by the new notification. Default = true.

3

This capability allows a MonitoredItem to be configured to sample, sample and report, or neither. Also to provide for independently enabling and disabling the reporting of notifications. Default = Reporting.

2

True = No historical data is read from the server, for this item, during the catchup process.

4

This value is based on a number of factors, including capabilities of the underlying system. The Server shall always return a revisedSamplingInterval that is equal or higher than the requested samplingInterval. If the requested samplingInterval is higher than the maximum sampling interval supported by the Server, the maximum sampling interval is returned.

5

This interval is defined in milliseconds. The value 0 indicates that the Server should use the fastest practical rate. The value -1 indicates that the default sampling interval defined by the publishing interval of the subscription is requested. A different sampling interval is used if the publishing interval is not a supported sampling interval. Any negative number is interpreted as -1. Default = -1.

6

UA Node ID in source, used for reading history, if the UA server has different nodeids for reading real-time data versus historical data. If empty, history reads defaults to using the 'SrcUaNodeId'.

7

Status: Report a notification ONLY if the StatusCode associated with the value changes;StatusOrValue: Report a notification if either the StatusCode or the value change. The Deadband filter can be used in addition for filtering value changes;StatusOrValueOrTimestamp: Report a notification if either StatusCode, value, or the SourceTimestamp changes. If a Deadband filter is specified, this trigger has the same behaviour as StatusOrValue.Default = StatusOrValueOrTimestamp.

8

If false, using current value datatype when writing this item to the server. If true, convert to datatype initially reported by server for this item, when writing to the server.|1

See also

Basic Item Properties

Predefined Item Properties

OPC DA Properties