Sounds like you will be writing a test terminal soon
Mmm.

How about:

Something like this maybe (a VB example)......?

Code:
Function ReceiveSerialData() As String
    ' Receive strings from a serial port.
    Dim returnStr As String = ""

    Using com1 As IO.Ports.SerialPort = _
            My.Computer.Ports.OpenSerialPort("COM1")
        Do
            Dim Incoming As String = com1.ReadLine()
            If Incoming Is Nothing Then
                Exit Do
            Else
                returnStr &= Incoming & vbCrLf
            End If
        Loop
    End Using

    Return returnStr
End Function