QuickOPC User's Guide and Reference
QueryCategoryConditions(IEasyAEClient,ServerDescriptor,Int64) Method



OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.AlarmsAndEvents Namespace > IEasyAEClientExtension Class > QueryCategoryConditions Method : QueryCategoryConditions(IEasyAEClient,ServerDescriptor,Int64) Method
The client object that will perform the operation.
The OPC server involved in the operation.
An event category Id for which the event conditions should be queried.
Finds out event conditions supported by given event category. Uses server descriptor for specifying the OPC server.
Syntax
'Declaration
 
<ExtensionAttribute()>
<ElementsNotNullAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function QueryCategoryConditions( _
   ByVal client As IEasyAEClient, _
   ByVal serverDescriptor As ServerDescriptor, _
   ByVal categoryId As Long _
) As AEConditionElementCollection
'Usage
 
Dim client As IEasyAEClient
Dim serverDescriptor As ServerDescriptor
Dim categoryId As Long
Dim value As AEConditionElementCollection
 
value = IEasyAEClientExtension.QueryCategoryConditions(client, serverDescriptor, categoryId)
[Extension()]
[ElementsNotNull()]
[NotNull()]
public static AEConditionElementCollection QueryCategoryConditions( 
   IEasyAEClient client,
   ServerDescriptor serverDescriptor,
   long categoryId
)
[Extension()]
[ElementsNotNull()]
[NotNull()]
public:
static AEConditionElementCollection^ QueryCategoryConditions( 
   IEasyAEClient^ client,
   ServerDescriptor^ serverDescriptor,
   int64 categoryId
) 

Parameters

client
The client object that will perform the operation.
serverDescriptor
The OPC server involved in the operation.
categoryId
An event category Id for which the event conditions should be queried.

Return Value

A collection of condition elements, one element for each condition of the given event category.
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 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.

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.

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