Option Explicit
Dim PortOpen As Boolean
 
Public Function PortTest(COMPortNummer As Integer) As Boolean
  MSComm1.CommPort = COMPortNummer
    On Error Resume Next
  MSComm1.PortOpen = True
 
  If Err = 0 Then
    PortTest = True
    MSComm1.PortOpen = False
  Else
    PortTest = False
    MSComm1.PortOpen = False
  End If
End Function