以2400bps从计算机发送任一字节数据，当单片机收到该数据后，在此数据前加上一序号然后连同此数据一起发送至计算机，当序号超过255时归零。 -2400bps from the computer to send any byte of data, when the microcontroller receives the data in this data with a serial number before then sent along with the data to the com