Excel VBA make a script asynchronous

Question

I have a script that can ping a list of computers and change their background color depending after the result it gets.

My problem is, that it blocks the entire excel file while it runs.

So my question is, how can I make it to run async?

Here is the code:

'ping
Function sPing(sHost) As String

Dim oPing As Object, oRetStatus As Object

Set oPing = GetObject("winmgmts:{impersonationLevel=impersonate}").ExecQuery _
  ("select * from Win32_PingStatus where address = '" & sHost & "'")

For Each oRetStatus In oPing
    If IsNull(oRetStatus.StatusCode) Or oRetStatus.StatusCode <> 0 Then
        sPing = "timeout" 'oRetStatus.StatusCode <- error code
    Else
        sPing = sPing & vbTab & oRetStatus.ResponseTime & Chr(10)
    End If
Next
End Function

Sub pingall_Click()
Dim c As Range
Dim p As String

Application.ScreenUpdating = True

For Each c In ActiveSheet.Range("A1:N50")
    If Left(c, 7) = "172.21." Then
    p = sPing(c)
        If p = "timeout" Then
            c.Interior.ColorIndex = "3"
        ElseIf p < 16 And p > -1 Then
            c.Interior.ColorIndex = "4"
        ElseIf p > 15 And p < 51 Then
            c.Interior.ColorIndex = "6"
        ElseIf p > 50 And p < 4000 Then
            c.Interior.ColorIndex = "45"
        Else
            c.Interior.ColorIndex = "15"

        End If
    End If
Next c

Application.ScreenUpdating = False

Answer 1

You can't do too much about this unfortunately since VBA runs in a single thread.

You can however introduce a degree of responsiveness by putting

VBA.DoEvents()

in various places in your code, ideally in the tight loops. In your case, put them just after the lines containing For. This pauses the VBA and flushes the event queue which will have the effect of making Excel responsive.

(Toggling the screen updating is a bad idea since you might leave things in a bad state if the function terminates unexpectedly. I'd remove the lines that do that if I were you.)

Answer 2

Excel can calculate "asynchronously". Call sPing as a function.

I'm not sure why your range is A1:N50. I assume one of the columns is the IP address, which I will assume as A. So your formula in column M will look like =sPing(A1).

As for the color coding, you can use conditional formatting.