Rs232 Send Receive Buffer

Hey guys, im using this code to send and receive via rs232 com port


problem is, i want to receive right after i send. I need to know how many bytes to receive, so before receiving, i run a function that figures that out. What i think is happening is that its running too fast and isnt waiting for the entire message to come back. Therefore the buffer is smaller than what is should be. Heres so code:

send function

VB Code:

Public Sub sendData(ByVal sTx As String)
 
        '----------------------
 
 
 
        '// Clear Tx/Rx Buffers
        moRS232.PurgeBuffer(Rs232.PurgeBuffers.TxClear Or Rs232.PurgeBuffers.RXClear)
 
        'sTx = sendBox.Text
        sendBox.Text = sTx
 
        If chkAddCR.Checked Then sTx += ControlChars.Cr
        moRS232.Write(sTx)
 
        debugThis("Message Sent: " + sTx)
 
        '//clear text box
        'sendBox.Text = String.Empty
        'sendBox.Refresh()
        lbHex.Items.Clear()
        If chkAutorx.Checked Then Button1_Click(Nothing, Nothing)
 
       receivedata()
 
    End Sub

receive function:

VB Code:

Private Sub receiveData()
 
 
        Try
            'first see how many bits are waiting to be read in
            bytesRemain = moRS232.InBufferCount.ToString()
            bytesRemaining.Text = bytesRemain
 
            ''MsgBox("going to read in " + CStr(bytesRemain) + " bytes")
 
            moRS232.Read(Int32.Parse(bytesRemain))
            receiveBox.Text = moRS232.InputStreamString
            receiveBox.ForeColor = Color.Black
            receiveBox.BackColor = Color.White
            '// Fills listbox with hex values
            Dim aBytes As Byte() = moRS232.InputStream
 
            Dim iPnt As Int32
            For iPnt = 0 To aBytes.Length - 1
                lbHex.Items.Add(iPnt.ToString & ControlChars.Tab & String.Format("0x{0}", aBytes(iPnt).ToString("X")))
            Next
 
            debugThis("Message Received: " + moRS232.InputStreamString)
        Catch Ex As Exception
            receiveBox.BackColor = Color.Red
            receiveBox.ForeColor = Color.White
            receiveBox.Text = moRS232.InputStreamString
            debugThis("Error: Could not read data")
 
            errorBox.Text = "Error: " & Ex.Message & "  data fetched: " & moRS232.InputStreamString
        End Try
    End Sub