X0                                                                                
-------------------------------I  I-----------------------------------------------------------------[  PLS    M10   ]
                                   啟動    
                     M10          M20 
------------------I  I-----------I / I-------.-------------------------------------------------------------(   M20  )
                                       啟動      I                                                                             啟動                                                              
                                                    I                                                                          
                                                    I
                                                    I
                                                    I
                     M10           M20      I
------------------I / I------------I  I------'  
                                       啟動                                                          
                            是已驗證過的程序,寫出來,與大家共享。