Record an ever changing cells value from Sheet 1 every 30 seconds into Sheet 2

Try this macro:

Public Sub test()
Dim Start As Variant, asd As Integer
Start = Timer
asd = 1
Do Until Sheets("Sheet1").Range("A1") = "BYE"
  Sheets("Sheet2").Cells(Rows.Count, 1).End(xlUp).Offset(1, 0) = Range("A1")
  Do Until asd = 0
  DoEvents
  asd = Int(Timer - Start) Mod 30
  Loop
  asd = 1
Loop
End Sub