'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function ReadMultipleItems( _
   ByVal client As IEasyDAClient, _
   ByVal itemArgumentsArray() As DAItemArguments, _
   ByVal readParameters As DAReadParameters _
) As DAVtqResult()

'Usage
 
Dim client As IEasyDAClient
Dim itemArgumentsArray() As DAItemArguments
Dim readParameters As DAReadParameters
Dim value() As DAVtqResult
 
value = IEasyDAClientExtension.ReadMultipleItems(client, itemArgumentsArray, readParameters)

[Extension()]
[NotNull()]
public static DAVtqResult[] ReadMultipleItems( 
   IEasyDAClient client,
   DAItemArguments[] itemArgumentsArray,
   DAReadParameters readParameters
)

[Extension()]
[NotNull()]
public:
static array<DAVtqResult^>^ ReadMultipleItems( 
   IEasyDAClient^ client,
   array<DAItemArguments^>^ itemArgumentsArray,
   DAReadParameters^ readParameters
) 

Parameters

client

The client object that will perform the operation.

This is typically the EasyDAClient object.

The value of this parameter cannot be null (Nothing in Visual Basic).

itemArgumentsArray

Array of item arguments objects (determine the OPC server and an OPC-DA item).

The value of this parameter cannot be null (Nothing in Visual Basic).

The individual elements of the parameter value cannot be null (Nothing in Visual Basic).

readParameters

The read parameters (such as data source or value age).

Because the DAReadParameters has an implicit conversion from System.Int32 and DADataSource, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use an integer (representing the value age in milliseconds), or an element of the DADataSource enumeration in place of this parameter, and the corresponding OPC DA read parameters object will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the DAReadParameters Constructor(Int32) or DAReadParameters Constructor(DADataSource) constructor instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

Return Value

The ReadMultipleItems method reads the data (values, timestamps and qualities) of multiple items from one or more OPC-DA servers. It uses the first available data from the server for each item; it does not wait until the quality becomes "uncertain" or "good". The function performs all individual operations in parallel, but only returns after all individual operations are completed (or their timeouts elapse).

This method does not throw an exception in case of OPC operation failures. Instead, the eventual exception related to each item is returned in Exception property of each returned OpcLabs.EasyOpc.DataAccess.OperationModel.DAVtqResult element.

The server(s) can be local or can be remotely accessed via DCOM.

Optionally, a specific data type can be requested, or an access path can be specified (OPC DA 1.0 only).

This method operates on multiple items at once. If you only have one item, you can use the ReadItem(IEasyDAClient,DAReadItemArguments) method instead.

The size of the input array will become the size of the output array. The element positions (indices) in the output array are the same as in the input array.

This is an extension method (info: C#, VB.NET). In languages that have support for extensions methods (such as C# and VB.NET), you can use the extension method as if it were a regular method on the object that is its first parameter. In other languages (such as with Python.NET), you will call the extension as a static method, and pass it the object on which it acts as its first parameter.

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows