public string conver()
        {
            string rus = "";
            XmlDocument xml = new XmlDocument();
            xml.Load("C:\\txcs.xml");
            XmlNode root = xml.SelectSingleNode("//纳伏表");
            string com1 = root.FirstChild.InnerText;
            string rate1 = root.LastChild.InnerText;
            SerialPort sm = new SerialPort();
            sm = com(com1, rate1);
            sm.Open();
            if (sm.IsOpen == false)
                MessageBox.Show("纳伏表串口未打开！！！");
            sm.WriteLine("CONF:VOLT:DC 100,DEF,(@2)");
            sm.WriteLine("CONF:VOLT:DC 100,DEF,(@1)");
            sm.WriteLine("SYSTem:REMote");//读一个数据设置
            for (int i = 0; i < 10; i++)
            {               
                System.Threading.Thread.Sleep(500);
                sm.WriteLine("READ?");
                byte[] ru;
                int Count;
                Count = sm.BytesToRead;
                ru = new Byte[Count];
                sm.Read(ru, 0, Count);
                for (int j = 0; j < Count; j++)
                {
                    rus =rus+ru[j];
                }

                             
            }
            sm.Close();
            return rus;
            
        }
用上面程序读取串口中的值时，发现串口缓冲器中一直没有值， sm.BytesToRead一直为零，但是用串口调试软件发送READ?后，可以从缓冲器中读取值，请问我上面那里出了问题，缓冲器中没有值？

谢谢，我改了试试看，