从Rs232读取字符串后得到两个空格

Question

我正在尝试从rs232读取。出于某种原因，有时（并非总是）在读取字符串后需要两个空格。

public static void Modem(Main ths)
    {


                mySerialPort = new SerialPort(Connection.ModemSerialPort);
                mySerialPort.BaudRate = 115200;
                mySerialPort.Parity = Parity.None;
                mySerialPort.StopBits = StopBits.One;
                mySerialPort.DataBits = 8;
                mySerialPort.Handshake = Handshake.None;

                mySerialPort.Open();
                mySerialPort.WriteLine("AT+VCID=1\r");
                mySerialPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);



    }
    private static void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e)
    {
        try
        {

            SerialPort sp = (SerialPort)sender;
            string indata = sp.ReadExisting();

            if (indata.Contains("=") == true)
            {


                string str = indata.Split('=').Last().Trim(); 
          }

所以我的结果是'测试'

我不知道为什么会这样。