EasyUA Reference
Read(IList<ReadValueId>) Method
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EasyUA Assembly > Advosol.EasyUA Namespace > Session Class > Read Method : Read(IList<ReadValueId>) Method

nodesToRead
List of Nodes and their Attributes to read. For each entry in this list, a StatusCode is returned, and if it indicates success, the Attribute Value is also returned.

Glossary Item Box

Reads values and attributes synchronously from OPC server.
The default requests settings are used. The timestamps are returned according the TimestampToReturn property (the default is SOURCE). MaxAge is set to 60000 (the cache value is returned unless the cache value is older than 1 minute).

Syntax

Visual Basic (Usage)Copy Code
Dim instance As Session
Dim nodesToRead As IList(Of ReadValueId)
Dim value As List(Of DataValue)
 
value = instance.Read(nodesToRead)

Parameters

nodesToRead
List of Nodes and their Attributes to read. For each entry in this list, a StatusCode is returned, and if it indicates success, the Attribute Value is also returned.

Return Value

A list with the read vakue for each node/attribute.

Remarks

The Read Service is used to read one or more attributes of one or more nodes. It allows also reading subsets or single elements of array values and to define a valid age of values to be returned to reduce the need for device reads. Like most other services, the read is optimized for bulk read operations and not for reading single Attribute values. Typically all Node Attributes are readable. For the Value Attribute the Read rights are indicated by the AccessLevel and UserAccessLevel Attribute of the Variable.

Requirements

Target Platforms: Windows 7/8/10, Windows Server 2003/2008/2012/2015, .NET4.x

See Also

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