SAFEARRAY - how to use

I am trying to write a VB code to use a DCOM through a DLL. The application is based on OPC HDA Server and I am using OPCHDAAuto.dll. I took the code from HDA specification and it is showed bellow:

Code:

---

Sub access_values()


    Dim AnOPCHDAServer As OPCHDAServer
    Dim ARealOPCHDAServer As String
    Dim ARealOPCNodeName As String
    Dim AnOPCHDAItemCollection As OPCHDAItems
    Dim AnOPCHDAItem As OPCHDAItem
    Dim ClientHandles(100) As Long
    Dim AnOPCHDAItemIDs(100) As String
   
    Dim AnOPCHDAItemServerHandles(10) As Long
    Dim AnOPCHDAItemServerErrors(10) As Long
    Dim AddItemCount As Long
    Dim i As Integer
   
    Set AnOPCHDAServer = New OPCHDAServer
    ARealOPCHDAServer = "HDATestSvr"
    ARealOPCNodeName = "localhost"
    AnOPCHDAServer.Connect ARealOPCHDAServer, ARealOPCNodeName
    Set AnOPCHDAItemCollection = AnOPCHDAServer.OPCHDAItems


    'Dim AnOPCHDAItemIDs() As String
    'Dim AnOPCHDAItemServerHandles As Long
    'Dim AnOPCHDAItemServerErrors As Long
    AddItemCount = 2
    For i = 1 To AddItemCount
        ClientHandles(i) = i
        AnOPCHDAItemIDs(i) = "A.A.A"
    Next i
    AnOPCHDAItemIDs(2) = "A.A.B"
    AnOPCHDAItemCollection.AddItems AddItemCount, _
                                    AnOPCHDAItemIDs, _
                                    ClientHandles, _
                                    AnOPCHDAItemServerHandles, _
                                    AnOPCHDAItemServerErrors
' add code to process any errors that are returned from 'the method, individual errors are reported in the Errors array



End Sub

---

The declaration, in the IDL file, of AddItems method of the IOPCHDAItems interface is :

Code:

---


        [helpstring("Adds OPCHDAItem objects to the collection")]
        HRESULT AddItems(
            [in]    LONG              NumItems,
            [in]    SAFEARRAY(BSTR) * ItemIDs,
            [in]    SAFEARRAY(LONG) * ClientHandles,
            [out]  SAFEARRAY(LONG) * ServerHandles,
            [out]  SAFEARRAY(LONG) * Errors);

---

and in VB is:

AddItems (NumItems As Long, ItemIDs() As String, ClientHandles() As Long, ByRef ServerHandles() As Long, ByRef Errors() As Long)

When I try to run it I get the message Type mismatch.

Someone could help me on that issue?

I appreciate any help.

I'm not sure how you call the function by I believe you must be passing fixed arrays in ServerHandles and Errors. Since these 2 parameters are "out" (Byref) parameters, the runtime engine checks if the parameter is exactly the type that is needed. Dynamic arrays and fixed arrays are different and so type mismatch is generated. Your code should be like this

Code:

---

Dim arrServerHandles() As Long  ' do not use Dim arrServerHandles(100) As Long
Dim arrErrors() As Long        ' do not use Dim arrErrors(100) As Long

...

Call <object>.AddItems(<param1>, <param2>, <param3>, arrServerHandles, arrErrors)

---

Hope it will help you :)

Thank for your help. The piece of code I wrote is working fine now.