QuickOPC User's Guide and Reference
ReadItemValueArrayOfDouble(IEasyDAClient,ServerDescriptor,DANodeDescriptor,DAReadParameters) Method



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OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.DataAccess.Extensions Namespace > IEasyDAClientExtension2 Class > ReadItemValueArrayOfDouble Method : ReadItemValueArrayOfDouble(IEasyDAClient,ServerDescriptor,DANodeDescriptor,DAReadParameters) Method
The client object that will perform the operation.
The OPC server involved in the operation.
The descriptor of the OPC node involved in the operation.
The read parameters (such as data source or value age).
Reads a value of named OPC item, and converts it to an array of System.Double. The value is requested from the OPC server using a corresponding data type.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function ReadItemValueArrayOfDouble( _
   ByVal client As IEasyDAClient, _
   ByVal serverDescriptor As ServerDescriptor, _
   ByVal nodeDescriptor As DANodeDescriptor, _
   ByVal readParameters As DAReadParameters _
) As Double()
 
'Usage
 
Dim client As IEasyDAClient
Dim serverDescriptor As ServerDescriptor
Dim nodeDescriptor As DANodeDescriptor
Dim readParameters As DAReadParameters
Dim value() As Double
 
value = IEasyDAClientExtension2.ReadItemValueArrayOfDouble(client, serverDescriptor, nodeDescriptor, readParameters)

Parameters

client
The client object that will perform the operation.
serverDescriptor
The OPC server involved in the operation.
nodeDescriptor
The descriptor of the OPC node involved in the operation.
readParameters
The read parameters (such as data source or value age).

Return Value

Returns a value of the OPC item, converted to a type indicated by the method name.
Exceptions
ExceptionDescription

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

The OPC "Classic" (or OPC XML-DA) operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause.

This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

Remarks
Using implicit conversions, you can pass an item ID in place of node descriptor. You can also pass a value age in place of read parameters
Requirements

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

See Also