System.IO.Ports.SerialPort com ;        private void Form1_Load(object sender, EventArgs e)
        {
            com = new System.IO.Ports.SerialPort("COM7", 9600, System.IO.Ports.Parity.None, 8, System.IO.Ports.StopBits.Two);
            com.Open();
        }        private void button1_Click(object sender, EventArgs e)
        {
            Byte[] buf = { 0x01, 0x03, 0x01, 0xF4, 0x00, 0x01, 0xC4, 0x04 };
            
            com.Write(buf, 0, buf.Length);
            
            textBox2.Text = buf.Length.ToString();            Byte[] readBuf = new Byte[512];            System.Threading.Thread.Sleep(1000) ;
            int readlen = com.Read(readBuf, 0, readBuf.Length);            if (readlen > 0)
            {
                string str = "", temp;                for (int i = 0; i < readlen; i++)
                {
                    temp = String.Format("{0:X2}", readBuf[i]);
                        str = str + temp + " ";
                }
                textBox1.Text = str; 
            }
            
        }
我这样写了一帧报文 可是在没有仪器表的时候执行以下窗体就卡住了
这是问什么呢? 请高手赐教  谢谢