VB里的MSComm和C#的serialPort

下面这段VB中的程序，换成C#中的serialPort该怎么写才好呢？我下面自己也写了个，但是运行报错。。
VB:
Dim Out(100) As Byte
Dim var As Variant
Dim ii As Integer
Public Function Comm()
    With MSC
        .CommPort = 5
        .Settings = "9600,n,8,1"
        .InBufferSize = 40
        .InputLen = 1
        .RThreshold = 1
        .InputMode = comInputModeBinary
        .InBufferCount = 0
        If Not .PortOpen Then
            .PortOpen = True
        End If
        .Output = "~HS"
        var = Null
        var = .Input
        DelayTime   '延时
        For ii = 2 To 81
            var = Null
            var = .Input
            Out(ii) = var(0)
            Tcm.Text = Tcm.Text & Chr(Out(ii))
        Next
        .RThreshold = 1
        .PortOpen = False
    End With
    num_s = right(Tcm.Text, 27)
    num_s = left(num_s, 1)
    Tcm.Text = ""
End Function

C#：
private void Comm()
{
    byte[] DataRead;
    int bytData;
    int bytnum;
    //serialPort.BaudRate = 9600;
    //serialPort.DataBits =8;
    //serialPort.PortName = "COM5";
    //serialPort.ReadBufferSize = 1024;
    //serialPort.WriteBufferSize = 1024;
    //serialPort.WriteTimeout = 200;
    serialPort.Close();
    serialPort.Open();
    serialPort.ReceivedBytesThreshold = 1;
    serialPort.DiscardInBuffer();
    serialPort.DiscardOutBuffer();
    string h = "~HS";
    Byte[] buff = System.Text.Encoding.Default.GetBytes(h);
    serialPort.Write(buff, 0, 3);
    Thread.Sleep(500);
    bytnum = serialPort.BytesToRead;
    DataRead = new byte[bytnum];
    for (int i = 2; i < 82; i++)
    {
        bytData = serialPort.ReadByte();
        DataRead[i] = (byte)bytData;
        Tcm.Text += DataRead[i];
    }
    serialPort.Close();
    int = Tcm.Text.Length;
    num_s = num_s.Substring(t - 27, 27);
    num_s = num_s.Substring(0, 1);
    Tcm.Text = "";
}
大家帮我看看，应该怎么改？
--------------------编程问答-------------------- 看看我的博客
C# 串口操作系列(1) -- 入门篇，一个标准的，简陋的串口例子。
C# 串口操作系列(2) -- 入门篇，为什么我的串口程序在关闭串口时候会死锁？
C# 串口操作系列(3) -- 协议篇，二进制协议数据解析

补充：.NET技术 ,  C#