AutoIt and Events generated by DLLs (OPC Server)

[ijourneaux]

I am using AutoIt to connect to an OPC server and acquire data using

$OPC_DA=ObjCreate("OPC.Automation")
$OPC_ID=$OPC_DA.Connect($WrapperOPCServer, $WrapperOPCNodeName)
$OPC_Groups = $OPC_DA.OPCGroups
$OPCGroup = $OPC_Groups.Add("SPWrapper")

$OPCGroupHandle=$OPCGroup.ClientHandle

$OPCItems=$OPCGroup.OPCItems

$OPCItems.AddItem($WrapperOPCFlag,$OPCGroupHandle)
$OPCItems.AddItem($WrapperOPCWeight,$OPCGroupHandle)
$OPCItems.AddItem($WrapperOPCWidth,$OPCGroupHandle)
$OPCItems.AddItem($WrapperOPCDiameter,$OPCGroupHandle)

At this point, I am just polling the OPC server for the data and determining if there is a change programatically. That works but I would prefer to avoid polling. The OPC.Automation event has a data change event.

I was wondering if I would be able to create an event handler in AutoIt that would allow me to react to the data change event when the data changed?

Here is what the event looks like for VB

Sub ConnectedGroup_DataChange(ByVal TransactionID As Long, ByVal NumItems As Long, ClientHandles() As Long, ItemValues() As Variant, Qualities() As Long, TimeStamps() As Date)
    ' We don't have error handling here since this is an event called from the OPC interface
    
    Dim i As Integer
    For i = 1 To NumItems
        ' Use the 'Clienthandles' array returned by the server to pull out the
        ' index number of the control to update and load the value.
        OPCItemValue(ClientHandles(i)).Text = ItemValues(i)
        
        ' Check the Qualties for each item retured here.  The actual contents of the
        ' quality field can contain bit field data which can provide specific
        ' error conditions.  Normally if everything is OK then the quality will
        ' contain the 0xC0
        If Qualities(i) And &HC0 Then
            OPCItemQuality(ClientHandles(i)).Text = "Good"
        Else
            OPCItemQuality(ClientHandles(i)).Text = Qualities(i)
        End If
    Next i
End Sub

Edited April 13, 2011 by ijourneaux

[PsaltyDS]

Your example shows COM object usage, not DLL calls. See ObjEvent() in the help file. For the more general information, see OBJ/COM Reference in the help file. Successfully using those COM events will depend on good documentation of the interface. Do you have a link to the documentation for that interface?

If it had been DLL usage, you would have registered a callback function with DllCallbackRegister(), again in the help file.