c#串口通讯中serialPort_DataReceive读取数据并显示的使用方法：

在使用下述代码中、串口设备一直发数据，PC读取的时候i总是会超出数组索引。求助解决办法。
private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
{
MsgRectextBox.AppendText("Recieved:" + "\r\n\r\n");
//int Length = serialPort1.BytesToRead;
byte[] MsgRec = new byte[1024*1024];
int Length = -1;
int i = 0;
serialPort1.Read(MsgRec, 0, 1024);
//builder.Clear();
MsgRecCount++;
while (MsgRec[2 + i] != 0xFF)
{
i++;
}
Length = Length + i + 4;
i = 0;
byte[] MsgRec1 = new byte[Length];
for (int j = 0; j < Length; j++)
{
MsgRec1[j] = MsgRec[j];
}
MsgRec1 = dataAnalyzer.ChangFE012FFFE002FE(MsgRec.Take(Length).ToArray());
string result = dataAnalyzer.ToHexString(MsgRec1);
MsgRectextBox.AppendText(MsgRecCount.ToString() + "-" + DateTime.Now.ToString("[yyyy-MM-dd HH:mm:ss:fff]") + "\r\n");
MsgRectextBox.AppendText(result + "\r\n");
}

//你的循环条件有问题，当然会超了
private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            MsgRectextBox.AppendText("Recieved:" + "\r\n\r\n");
            //int Length = serialPort1.BytesToRead;
            byte[] MsgRec = new byte[1024 * 1024];
            int Length = -1;
            int i = 0;
            serialPort1.Read(MsgRec, 0, 1024);
            //builder.Clear();
            MsgRecCount++;
            while (MsgRec[2 + i] != 0xFF)
            {
                i++;
                if (i + 2 >= 1024)//大于等于数组长度时退出循环
                    break;//加上这个应该就不会超了
            }
            Length = Length + i + 4;
            i = 0;
            byte[] MsgRec1 = new byte[Length];
            for (int j = 0; j < Length; j++)
            {
                MsgRec1[j] = MsgRec[j];
            }
            MsgRec1 = dataAnalyzer.ChangFE012FFFE002FE(MsgRec.Take(Length).ToArray());
            string result = dataAnalyzer.ToHexString(MsgRec1);
            MsgRectextBox.AppendText(MsgRecCount.ToString() + "-" + DateTime.Now.ToString("[yyyy-MM-dd HH:mm:ss:fff]") + "\r\n");
            MsgRectextBox.AppendText(result + "\r\n");
        }