FindEventCategory Method

Attempts to find a specified event category in the OPC server, and returns information about it when found.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
Public Shared Function FindEventCategory( _
   ByVal client As IEasyAEClient, _
   ByVal serverDescriptor As ServerDescriptor, _
   ByVal categoryId As Long, _
   ByRef categoryElement As AECategoryElement _
) As Boolean

'Usage
 
Dim client As IEasyAEClient
Dim serverDescriptor As ServerDescriptor
Dim categoryId As Long
Dim categoryElement As AECategoryElement
Dim value As Boolean
 
value = IEasyAEClientExtension2.FindEventCategory(client, serverDescriptor, categoryId, categoryElement)

[Extension()]
public static bool FindEventCategory( 
   IEasyAEClient client,
   ServerDescriptor serverDescriptor,
   long categoryId,
   out AECategoryElement categoryElement
)

[Extension()]
public:
static bool FindEventCategory( 
   IEasyAEClient^ client,
   ServerDescriptor^ serverDescriptor,
   int64 categoryId,
   [Out] AECategoryElement^ categoryElement
)

Parameters

client

The client object that will perform the operation.

This is typically the OpcLabs.EasyOpc.AlarmsAndEvents.EasyAEClient object.

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

serverDescriptor

The OPC server involved in the operation.

Because the OpcLabs.EasyOpc.ServerDescriptor has an implicit conversion from System.Guid, System.String and OpcLabs.EasyOpc.ServerElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a GUID (representing the CLSID of the server), a string (representing the so-called OPC server descriptor string, such as a ProgID or the URL of the server), or a OpcLabs.EasyOpc.ServerElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC server descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the FromGuid, FromString or FromServerElement static method instead.

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

categoryId

Event category ID to be found.

categoryElement

Information about the event category, if found.

The value of this parameter can be null (Nothing in Visual Basic).

Return Value

Returns 'true' if the event category has been found, 'false' otherwise.

Exceptions

Exception Description

Exception	Description
System.ArgumentNullException	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.
System.ArgumentOutOfRangeException	The value of an argument is outside the allowable range of values as defined by the invoked method. 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.
OpcLabs.EasyOpc.OperationModel.OpcException	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.

System.ArgumentNullException

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.

System.ArgumentOutOfRangeException

The value of an argument is outside the allowable range of values as defined by the invoked method.

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.

OpcLabs.EasyOpc.OperationModel.OpcException

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

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.

Requirements

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

Reference

IEasyAEClientExtension2 Class
IEasyAEClientExtension2 Members

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