Disabling a Time Function

[KeillRandor]

I searched the forum and couldn't find an answer to this.

I'm creating a system that will allow staff to scan their work-card to show when they arrived. What I need is a cell that dynamically gets the current system time and enters it into a cell. Once this time value is entered I would like the cell to become just a value i.e. no function.

Here's what I have.

I have a cell with the formula -

=IF(ISBLANK(D9),"FAIL",showTime())

The showTime function is in the Module

Function showTime() As Variant
showTime=Now
End Function

This works correctly on the first usage but then the value gets updated every time the sheet opens and sometimes when I'm editing other Functions.

So is there a way of making a function run once, or disabling a function, preferably I would like to change the cell contents to a value.

Any help would be appreciated.

Keill

[KeillRandor]

My new plan is the following -
I have a new Sub called output that I pass the Cell reference that calls the sub i.e For the cell A1 it would contain the formula

=output(A1)

What I want output to do is check if the cell calling the sub contains a function - which it has to - if so use the Cells.ClearContents method to erase the formula and the Cells.Value to insert a value.

Here's what output looks like -

Sub output(cellReference As Range)

Dim cellcolumn, cellrow
cellcolumn = cellReference.Cells.Column
cellrow = cellReference.Cells.Row

IF(cellreference.HasFormula) Then

'THIS IS WHERE THE PROBLEM IS
'I'M NOT SURE IF THE SYNTAX IS CORRECT
cellReference.Cells.ClearContents
cellReference.Cells.Value = Now

'THE ABOVE DID NOT WORK
'SO I TRIED

Worksheet("Sheet1").Activate
Cells(cellrow,cellcolumn).ClearContents
Cells(cellrow,cellcolumn).Value = Now

END IF

END SUB

It appears as though I can access the properties of the Cells class but can't use the modifiers.

I tried

Worksheet("Sheet1").Activate
Cells(10,10).Value = 666

as a test but nothing happened.

So my question is this - is there anything else I should be doing?