Option Explicit
Private Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAccess As Long, ByVal bInheritHandle As Long, ByVal dwProcessId As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function EnumProcesses Lib "PSAPI.DLL" (lpidProcess As Long, ByVal cb As Long, cbNeeded As Long) As Long
Private Declare Function EnumProcessModules Lib "PSAPI.DLL" (ByVal hProcess As Long, lphModule As Long, ByVal cb As Long, lpcbNeeded As Long) As Long
Private Declare Function GetModuleBaseName Lib "PSAPI.DLL" Alias "GetModuleBaseNameA" (ByVal hProcess As Long, ByVal hModule As Long, ByVal lpFileName As String, ByVal nSize As Long) As Long
Private Const PROCESS_VM_READ = &H10
Private Const PROCESS_QUERY_INFORMATION = &H400
 
Public Function EstaCorriendo(ByVal NombreDelProceso As String) As Boolean
    Const MAX_PATH As Long = 260
    Dim lProcesses() As Long, lModules() As Long, N As Long, lRet As Long, hProcess As Long
    Dim sName As String
    NombreDelProceso = UCase$(NombreDelProceso)
    ReDim lProcesses(1023) As Long
 
    If EnumProcesses(lProcesses(0), 1024 * 4, lRet) Then
        For N = 0 To (lRet \ 4) - 1
            hProcess = OpenProcess(PROCESS_QUERY_INFORMATION Or PROCESS_VM_READ, 0, lProcesses(N))
            If hProcess Then
                ReDim lModules(1023)
                If EnumProcessModules(hProcess, lModules(0), 1024 * 4, lRet) Then
                    sName = String$(MAX_PATH, vbNullChar)
                    GetModuleBaseName hProcess, lModules(0), sName, MAX_PATH
                    sName = Left$(sName, InStr(sName, vbNullChar) - 1)
 
                    If Len(sName) = Len(NombreDelProceso) Then
                        If NombreDelProceso = UCase$(sName) Then EstaCorriendo = True: Exit Function
                    End If
                End If
            End If
            CloseHandle hProcess
        Next N
    End If
End Function
 
 

Private Sub Form_Load()
    Timer1.Enabled = True
    Timer1.Interval = 100
    Me.BackColor = vbRed
End Sub
 
Private Sub Timer1_Timer()
    If EstaCorriendo("calc.exe") Then
        Me.BackColor = vbGreen
    Else
        Me.BackColor = vbRed
    End If
End Sub
 
 

Public Variable As String
 
Private Sub Command1_Click()
    CallByName Me, "Variable", VbLet, "Hola"
    MsgBox Variable
End Sub
 
Private Sub Form_Load()
    Variable = "Manzana"
    MsgBox Variable
End Sub
 
 

Sub chgVar(tVar As String, ByVal valor As String)
    tVar = valor
End Sub
 
Private Sub Form_Load()
    Dim Variable As String
    Variable = "No entiendo muy bien"
    Debug.Print Variable
    Call chgVar(Variable, "asi? o como?")
    Debug.Print Variable
End Sub
 

Sub chgVar(tVar As String, ByVal valor As String)
    tVar = valor
End Sub
 
Private Sub Form_Load()
    Dim Variable As String
    Variable = "No entiendo muy bien"
    Debug.Print Variable
    Text1.Text = "Variable"
    Call chgVar(Text1.Text, "asi? o como?")
    Debug.Print Variable
End Sub