Question

Excel Instances- Refering to the Instance in VBA

Asked by: kyle972

I need to open multiple instances of excel and be able to control each instance in VBA. I currently am storing the information for each instance when it is opened so that I can refer back to it. The problem with this approach is:

1. You have to open the instance using VBA in order to have a reference to it
2. It is unstable, any VBA error will erase the public variables where the instances are stored as "Microsoft Excel"
3. No way to store distinguishing instance information in a spreadsheet..because all instance variables are "Microsoft Excel"

I have found the following code that returns the handle for each excel instance running and stores it in an array. (This is a good start to being able to distinguish each instance and not have to deal with the generic "Microsoft Excel" reference. The two things I am looking for:

1. How do I take the handle information for each instance being stored in the array and use that in VBA to control that instance?

2. I need to be able to distinguish the instances so I know what handle refers to what instance. Perhaps through a workbook name in that instance or some other method so I know what instance of excel each handle is referring to.

My end goal:

Be able to record instance variables or handles into a spreadsheet with some unique identifiers so I can then reference that spreadsheet and pull the correct instance information to control the instance in VBA. I do not want to have to store everything in public variables or have to open the instance from VBA in order to have the ability to refer to it.



Option Explicit 
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long 
Private Declare Function GetNextWindow Lib "user32" Alias "GetWindow" (ByVal hwnd As Long, ByVal wFlag As Long) As Long 
Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" (ByVal hwnd As Long, ByVal lpClassName As String, ByVal nMaxCount As Long) As Long
Public hWndArray() As Long 

Private Const GW_HWNDNEXT = 2 
 
Sub xlInstances() 
  Dim hwnd As Long, lRet As Long
  'Dim hWndArray() As Long
  Dim i As Integer
  Dim sClassBuffer As String 
  i = 0
  hwnd = FindWindow("XLMAIN", vbNullString)
  If hwnd <> 0 Then
    ReDim hWndArray(i)
    hWndArray(i) = hwnd
    Do
      hwnd = GetNextWindow(hwnd, GW_HWNDNEXT)
      If hwnd = 0 Then Exit Sub
      sClassBuffer = String(255, 0)
      lRet = GetClassName(hwnd, sClassBuffer, Len(sClassBuffer))
      sClassBuffer = Left(sClassBuffer, InStr(1, sClassBuffer, Chr(0), vbTextCompare) - 1)
      If UCase(sClassBuffer) = "XLMAIN" Then
        i = i + 1
        ReDim Preserve hWndArray(i)
        hWndArray(i) = hwnd
      End If
    Loop
  End If 
 
 
End Sub

                                  
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Asked On
2009-11-07 at 07:14:12ID24880460
Tags

Excel

,

VBA

Topic

Microsoft Excel Spreadsheet Software

Participating Experts
3
Points
500
Comments
6

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Answers

 

by: TiranDagan55Posted on 2009-11-08 at 00:48:38ID: 25769840

have you considered using registry variables or data files to exchange information amoung the instances?

 

by: kyle972Posted on 2009-11-08 at 12:36:56ID: 25771765

It is more complicated than just storing data.  I need to be able to refer to each instance from the code that is running in the main instance.

Example:
Run Macro in Instance 1.
The macro does somethings in instance 1....then
Opens a new instance #2 and does some things in that instance.
Then activates instance 1 and use information from instance 2 to populate cells

I currently have this code working, but have to store each instance variable in a public variable. This creates 2 problems: I can only refer to an instance opened by the macro and it is unstable and easy for the pubic variables to be cleared. I need a more permanent way to refer to an instance in excel. I thought storing handles for each instance was a building block to the solution and that is what the posted code does.

 

by: StellanRosengrenPosted on 2009-11-08 at 16:16:33ID: 25772691

Hi kyle972,
I don't think you can get the object reference from the windows handle. The GetObject function with the class argument "Excel.Application" does not return references to all instances. But, it might be possible to use the GetObject function with the pathname argument if you make sure that each running instance has an open workbook and you use the fullname of that workbook as the argument. It can be an empty workbook and it can be hidden.
Since the object returned by GetObject will be a workbook, you will of course have to use the application property like in this example.

Set myXlApp1 = GetObject("C:\wkb1.xls").Application

You can easily restore the references in your main application.
Could this solution be useful in your case? Please tell me if you need further assistance.

Kind regards,
Stellan

 

by: kyle972Posted on 2009-11-08 at 18:20:23ID: 25773039

Stellan,

That workaround will do the trick I think. The only problem I am having now is I don't want to use GetObject(filename) unless that file is actually open in an instance of excel. If I use the GetObject() without the file already being opened then it causes it to open in Read Only when I actually want to open it.

Using the GetObject() I can refresh all my instance references, however, not all of them will actually be open and that causes the issue I am having above. How can I check to see if the file is already open in any instance before using the GetObject()

 

by: StellanRosengrenPosted on 2009-11-09 at 03:05:15ID: 25774832

If you use GetObject with a filename that is not open in any running instance, it looks like the workbook will open in the main instance (as a hidden workbook). So, if you add a test to identify where the workbook was opened, like
Set myXlApp1 = GetObject("C:\wkb1.xls").Application
If Thisworbook.Application.Hwnd = myXlApp1.Hwnd Then
  'Was not open before!
  myXlApp1.Workbooks("wkb1.xls").Close
  Set myXlApp1=Nothing
Else
  'Found a running instance
End If

Of course there are other ways to do the test. For example you could loop through all open workbooks in the reference returned from GetObject and check if there is a match with another workbook in the list. Then you know that you did not get a new reference.

I hope this will work for you.

 

by: roryaPosted on 2009-11-09 at 06:39:45ID: 25776260

If you want to check if the workbook is already opened, then you will need to use code like the original FindWindow code to locate each instance of an XLMAIN class, then within that class locate the XLDESK window, then loop through all the EXCEL7 windows within that. Using FindWindowEx, the function below will try to locate a workbook name for a given application window handle:

Function GetWorkbookHandle(strWBCaption As String, lngHWnd As Long) As Long
   Dim hwnd As Long, hWndDesk As Long
   Dim strText As String
   hWndDesk = FindWindowEx(lngHWnd, 0&, "XLDESK", vbNullString)
   If hWndDesk <> 0 Then
      hwnd = FindWindowEx(hWndDesk, hwnd, "EXCEL7", strWBCaption)
      If hwnd <> 0 Then GetWorkbookHandle = hwnd
   End If
End Function
                                              
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