Finds out event attributes that the server can provide as part of an event notification within a given event category. Uses computer name and server class for specifying the OPC server.
Syntax
'Declaration
<ExtensionAttribute()>
<ElementsNotNullAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function QueryCategoryAttributes( _
ByVal As IEasyAEClient, _
ByVal As String, _
ByVal As String, _
ByVal As Long _
) As AEAttributeElementCollection
'Usage
Dim client As IEasyAEClient
Dim machineName As String
Dim serverClass As String
Dim categoryId As Long
Dim value As AEAttributeElementCollection
value = IEasyAEClientExtension.QueryCategoryAttributes(client, machineName, serverClass, categoryId)
[Extension()]
[ElementsNotNull()]
[NotNull()]
public static AEAttributeElementCollection QueryCategoryAttributes(
IEasyAEClient ,
string ,
string ,
long
)
[Extension()]
[ElementsNotNull()]
[NotNull()]
public:
static AEAttributeElementCollection^ QueryCategoryAttributes(
IEasyAEClient^ ,
String^ ,
String^ ,
int64
)
Parameters
- client
- The client object that will perform the operation.
- machineName
- Name of the machine. Determines the computer on which the OPC server is located. May be an empty string, in which case the OPC server is assumed to exist on the local computer or at the computer specified for it by DCOM configuration.
- serverClass
- Contains ProgID of the OPC server.
- categoryId
- An event category Id for which the event attributes should be queried.
Return Value
A collection of attribute elements, one element for each attribute of the given event category.
Exceptions
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. |
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