Question

I am trying to write a macro in VB for an Excel spreadsheet which is executed in specific intervals which are defined by a value (in Hz) contained in the spreadsheet itself. My problem is that the code I found for accomplishing an automatic macro in this way appears to only allow for second accuracy, so any frequencies above 1Hz are not possible. I would like to be able to get up to around 10Hz if possible, which would require millisecond accuracy.

I am new to VB, so I do not know much about it. Here is the code:

Sub Macro2()
    Range("K1").Select
    Dim f As Single
    f = ActiveCell.Value
    Dim t As Integer
    t = 1 / f
    dTime = Now + TimeSerial(0, 0, t)
    Application.OnTime dTime, "Macro2"
    Range("J1").Select
    Dim c As Integer
    c = ActiveCell.Value
    c = c Xor 1
    ActiveCell.Value = c
End Sub

Is there any way to get Millisecond accuracy using this method?

Answer 1

Excel does not work in anything less than whole seconds.

There are a couple of issues with your code:

You define Dim t As Integer and go on to assign t = 1 / f which means that for any value of f greater than one, t will be zero (because it’s constrained to be an integer).

TimeValue() can only work in whole seconds, so it doesn’t matter whether t is a fraction or not because TimeValue() will discard any fractional part.

The macro will run with t being zero, but it’s uncontrolled and irregular. I suspect that is part of the reason that Excel VBA doesn’t work in milliseconds: the execution of VBA code just isn’t accurate enough.

Unfortunately, because VBA can’t work in milliseconds, I can’t suggest a way of making it do so.