双机通信，甲机乙机通信 甲机发送信号，乙机接受提示，用户确定，乙机再反馈甲机，甲机接受提示，用户确定，甲机发送指令，乙机接受，用户确定，乙机工作-Two-machine communication, A Machine B Machine Communication A machine sends a signal, B receive prompt the user to determine the B machine and then feedback A machine, a m