Thanks Bob,
Your'e right, a simple script is best.
Sub Main()    Console.PrintLine "Weather Alert... script initiated"
    Console.PrintLine "Closing roof/shutter."
    If Telescope.Connected Then
        Console.PrintLine "...scope is connected, parking now"
        Telescope.Park     ' Default setting in ACP, this parks and closes the dome/roof in that order
        Console.PrintLine "...scope is parked"
    End If
    Console.PrintLine "Weather Safety...script completed successfully"
End Sub
When I use the above script I get:

Weather Alert... script initiated
Closing roof/shutter.
...scope is connected, parking now
...scope is parked
Weather Safety...script completed successfully

I think that's the best I can ask for now. Thanks again.

Since there is no readable limit switch, I can never be absolutely shure the shutter is really closed, I will have to trust the system or make an independent alarm.
Maybe something with a retro reflector on the shutter and a photo-electric sensor that checks if the shutter is closed.