vb的打印，调用打印函数，先测试打印机向串口发数据，将字符串转为十六进制表示的字符串，从接收缓冲区读取数据，关闭串口事件响应-vb print, call the print function, send the first test the printer to the serial data string to hexadecimal string from the receive buffer read data off the serial port incident response