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 callback As AsyncCallback Dim userData As Object Dim value As IAsyncResult value = instance.BeginRead(nodesToRead, callback, userData) | |
| C# | |
|---|---|
public IAsyncResult BeginRead( IList<ReadValueId> nodesToRead, AsyncCallback callback, object userData ) | |
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.
- callback
- The callback to call when the async processing completes.
- userData
- The user data that is passed to the callback.
Return Value
The object that must be passed to the EndRead method.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