利用电脑的串口对继电器进行“吸和”，“断开”的控制。进而利用继电器的常开或者常闭触点去控制各种用电器，设备的“开”与“关”。它分为上位机和下位机-Use computer' s serial port to relay " and suck" , " off" control. Further use of the relay normally open or normally closed contacts to control all kinds of