最近工作之余，在学习一些串口得知识，或许是基础太差了，总是碰到一些问题，解决不了。
  请教大家一下。
  在串口传送一些大得数组，总是会丢失一些数据，例如我发送一个02 01 00 00 00 00 00 00 00 00 00 20 00 00 00 00 00 00 00 00 00 00 00 00 00 23，当程序刚运行时，

第一次在接收端可以接收得数据02 01 00 00 00 00 00 00 00 00 00 20 00 00 00 00 00 00 00 00 00 00 00 00 00 23

第二次再发送同样得数组接收得就是02 01 00 00 00 00 00 00

第三次，第四次..再发送同样得数组接收得是00 00 00 20 00 00 00 00 00 00 00 00 00 00 00 00 00 23 02 01 00 00 00 00 00 00
SerialPort1.ReceivedBytesThreshold 我也有设置过，但是还是总是丢失。
当发送一个02 01 02 00 00 00 00 00 01这样得数组就不会丢失数据。
发送端代码：
      

 Sub sendmessage()
        Dim i As Integer
        'Me.SerialPort1.DiscardInBuffer()
        If CheckBox2.Checked = True Then
            strHex = sendtxt.Text
            ReDim byteSEnd(Len(strHex) \ 3)
            For i = 1 To Len(strHex) Step 3
                byteSEnd((i - 2) / 3) = Val("&H" & Mid(strHex, i, 3))
            Next
            Me.SerialPort1.Write(byteSEnd, 0, byteSEnd.Length)
            readmessage()
        Else
            Me.SerialPort1.Write(sendtxt.Text)
            readmessage()
        End If
        If CheckBox1.Checked = True Then
            Timer1.Enabled = True
            Timer1.Interval = TextBox1.Text
        End If
    End Sub

接收端代码：
   

Sub readmessage()
        If CheckBox2.Checked = True Then
            Dim j As Integer
            Dim temp As String
            Dim mSize As Integer = Me.SerialPort1.BytesToRead
            ReDim receiveData(mSize - 1)
            Me.SerialPort1.Read(receiveData, 0, mSize)
            Me.SerialPort1.ReceivedBytesThreshold = 1000
            If mSize > 0 Then
                For j = 0 To UBound(receiveData)        ' 根据接收到的16进制数据长度，逐个字节显示
                    temp = Hex(receiveData(j))
                    If Len(temp) = 1 Then
                        temp = "0" & Hex(receiveData(j))
                    Else
                        temp = Hex(receiveData(j))
                    End If
                    Receivedtxt.Text = Me.Receivedtxt.Text + temp + " "
                Next j
            End If
        Else
            Receivedtxt.AppendText(Me.SerialPort1.ReadExisting)
            'System.Threading.Thread.Sleep(1000)
            Me.Receivedtxt.ScrollToCaret()

        End If
        Me.messagelab2.Text = "信息已传输完毕"
    End Sub

请大家支招，怎样避免在传送大数组时丢失数据，谢谢~~