串口上位机控制八路继电器控制51单片机板程序，串口必须调到com1，否则无法打开上位机-PC serial port control eight-way relay control panel program, a serial port must be transferred to the com1, otherwise unable to open the upper machine。

串口控制单片继电器，使用VB编写，方便各位修改- Serial control of single-chip relay, using VB to prepare, to facilitate you to amend