Question

How does one execute some VBA code periodically, completely automated?

Answer 1

You can use Application.OnTime to schedule a macro to be executed periodically. For example create a module with the code below. Call ‘Enable’ to start the timer running.

It is important to stop the timer running when you close your workbook: to do so handle Workbook_BeforeClose and call ‘Disable’

Option Explicit  Private m_dtNextTime As Date Private m_dtInterval As Date  Public Sub Enable(Interval As Date)     Disable     m_dtInterval = Interval     StartTimer End Sub  Private Sub StartTimer()     m_dtNextTime = Now + m_dtInterval     Application.OnTime m_dtNextTime, 'MacroName' End Sub  Public Sub MacroName()     On Error GoTo ErrHandler:     ' ... do your stuff here      ' Start timer again     StartTimer     Exit Sub ErrHandler:     ' Handle errors, restart timer if desired End Sub  Public Sub Disable()     On Error Resume Next ' Ignore errors     Dim dtZero As Date     If m_dtNextTime <> dtZero Then         ' Stop timer if it is running         Application.OnTime m_dtNextTime, 'MacroName', , False         m_dtNextTime = dtZero     End If     m_dtInterval = dtZero End Sub 

Alternatively you can use the Win32 API SetTimer/KillTimer functions in a similar way.