Local oCom as Object 

oCom = thisform.mscomm1

For i=1 To 10

   Try 

     oCom._CommPort =i

     oCom.portOpen=.t.

     oCom.portOpen =.f.

     Thisform.combo1.AddItem('COM'+Alltrim(Str(i)))

   Catch 

   EndTry 

EndFo