Thanks Tusharm,
I have managed to get the macro to run every minute by adapting Pearsons formula. WIll tackle the 0800 and 1400 hrs a little later. Thanks for your help.
For others who are also searching for a similar macro, here is the code:
Public Declare Function SetTimer Lib "user32" ( _
ByVal HWnd As Long, _
ByVal nIDEvent As Long, _
ByVal uElapse As Long, _
ByVal lpTimerFunc As Long) As Long
Public Declare Function KillTimer Lib "user32" ( _
ByVal HWnd As Long, _
ByVal nIDEvent As Long) As Long
Public TimerID As Long
Public TimerSeconds As Single
Sub StartTimer()
TimerSeconds = Range("A1").Value 'enter in cell(A1) the seconds between updates
TimerID = SetTimer(0&, 0&, TimerSeconds * 1000&, AddressOf TimerProc)
End Sub
Sub EndTimer()
On Error Resume Next
KillTimer 0&, TimerID
End Sub
Sub TimerProc(ByVal HWnd As Long, ByVal uMsg As Long, _
ByVal nIDEvent As Long, ByVal dwTimer As Long)
MyMacro 'the name of your macro to run
End Sub