X0                                                                                
-------------------------------I  I-----------------------------------------------------------------[  PLS    M10   ]
                                   啟動(dòng)    



                     M10          M20
------------------I  I-----------I / I-------.-------------------------------------------------------------(   M20  )
                                       啟動(dòng)      I                                                                             啟動(dòng)                                                              
                                                    I                                                                          
                                                    I
                                                    I
                                                    I
                     M10           M20      I
------------------I / I------------I  I------'  
                                       啟動(dòng)                                                          

                            是已驗(yàn)證過(guò)的程序，寫出來(lái)，與大家共享。