Required help on SendKeys To Hidden Application Object

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C#

VB

VBA

I want to send commands to my application even if it is not visible. I have below code, but it is not working as the Excel application is not visible. (I Know code without using sendkeys/postmessage) But here excel application is just taken as example. I have one business object application which I want to operate using sendkeys/postmessage)
Please help me.


I have below code but not solving my problem.

Option Explicit
Declare Function FindWindowX Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, _
ByVal hWnd2 As Long, ByVal lpsz1 As Long, ByVal lpsz2 As Long) As Long
 
Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
 
Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, _
ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
 
Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Integer, ByVal lParam As Integer) As Long
 
Private Const WM_KEYDOWN = &H100
'Private Const WM_KEYUP = &H101

Sub MyProc2()
   Dim xl As New Excel.Application
   xl.Workbooks.Add
   xl.Visible = False
   Dim hWind As Variant
   Dim cWind As Variant
   hWind = xl.hwnd
   cWind = FindWindowX(hWind, 0, 0, 0)
   Debug.Print PostMessage(cWind, WM_KEYDOWN, vbKeyH, 0) 'type H
   Debug.Print PostMessage(cWind, WM_KEYDOWN, vbKeyI, 0) 'type I
   Debug.Print PostMessage(cWind, WM_KEYDOWN, 13, 0) 'Press Enter Key
   'Below to open Find & Replace window (Ctrl+H)
   Debug.Print PostMessage(cWind, WM_KEYDOWN, 17, 0) 'Press Ctrl Key
   Debug.Print PostMessage(cWind, WM_KEYDOWN, vbKeyH, 0)  'Press H Key
   Debug.Print cWind ' Everytime output is different
   Debug.Print hWind ' Everytime output is different
End Sub