TDR/TDT Measurement

Dim rm As VisaComLib.ResourceManager

Dim vna As VisaComLib.FormattedIO488

Sub Message(msg As String)

    Dim NumDmy As Integer

    'Syncronize to VNA

    vna.WriteString "*OPC?"

    NumDmy = vna.ReadNumber

    'Write Message

    MsgBox msg, vbOKOnly

End Sub

Sub TDRTDTMeasure()

    On Error GoTo errorhandler

    Set rm = New VisaComLib.ResourceManager

    Set vna = New VisaComLib.FormattedIO488

    ' Set VNA Address

    Set vna.IO = rm.Open("TCPIP0::K-N5232B-40046::hislip0::INSTR")

    vna.IO.Timeout = 90000

    ' Clear Excel Sheet Cells

    Range("D5:F5").ClearContents

    With vna

        Dim i As Integer

        ' Set DUT Topology to Differential 2-Port

        .WriteString ":CALC:TDR:DEV DIF2"

        ' Desckew and Loss Compensation
       '

        ' Desckew

        .WriteString ":SENSe:CORR:TDR:EXTension:AUTO:IMMediate", True

        .WriteString "*OPC?", True

        NumDmy = .ReadNumber

         '
        ' Loss Compensation, thru

         MsgBox "Connect thru between ports 1 and 3.", vbOKOnly

        .WriteString ":SENS:CORR:TDR:COLL:DLC:THRU 1,3", True

        .WriteString "*OPC?", True

        NumDmy = .ReadNumber

        MsgBox "Connect thru between ports 2 and 4.", vbOKOnly

        .WriteString ":SENS:CORR:TDR:COLL:DLC:THRU 2,4", True

        .WriteString "*OPC?", True

        NumDmy = .ReadNumber

        ' Loss Compensation, thru

        MsgBox "Connect a Load to the ports 1,2,3,4.", vbOKOnly

        .WriteString ":SENS:CORR:TDR:COLL:DLC:LOAD 1", True

        .WriteString "*OPC?", True

        NumDmy = .ReadNumbe

        .WriteString ":SENS:CORR:TDR:COLL:DLC:LOAD 2", True

        .WriteString "*OPC?", True

        NumDmy = .ReadNumber

        .WriteString ":SENS:CORR:TDR:COLL:DLC:LOAD 3", True

        .WriteString "*OPC?", True

        NumDmy = .ReadNumber

        .WriteString ":SENS:CORR:TDR:COLL:DLC:LOAD 4", True

        .WriteString "*OPC?", True

        NumDmy = .ReadNumber

        ' Save the data  to finish the Deskew and Loss Compensation

        .WriteString ":SENS:CORR:TDR:COLL:DLC:SAVE", True

        .WriteString "*OPC?", True

        NumDmy = .ReadNumber

        ' Set Rise Time

        .WriteString "CALC:PAR:COUN?" 'Get number of traces

        For i = 1 To .ReadNumber

            .WriteString ":CALC:TDR:MEAS" + CStr(i) + ":TIME:STEP:RTIM:THR T2_8" 'Threshold

            .WriteString ":CALC:TDR:MEAS" + CStr(i) + ":TIME:STEP:RTIM 50e-12"   'Rise Time

        Next i

        ' Measure

        Message "Connect DUT to cables." + vbCrLf + "Press OK to execute measurement."

        .WriteString ":SENS:TDR:SWE:SING;*OPC?"

        NumDmy = .ReadNumber

        ' Auto Scale for all traces

        .WriteString ":DISP:TDR:SCAL:AUTO"

        ' Read Rise Time of Tr 5 (Tdd21)

        Cells(5, 4) = "Rise Time"

        .WriteString ":CALC:TDR:MEAS5:TTIM:STAT ON"

        .WriteString ":CALC:TDR:MEAS5:TTIM:THR T2_8"

        .WriteString ":CALC:TDR:MEAS5:TTIM:DATA?"

        Cells(5, 6) = .ReadNumber

        ' Restore TDR GUI

        .WriteString ":DISP:TDR:MIN:STAT OFF"

        Message "Finished TDT/TDT Measurement."

    End With

    vna.IO.Close

    Exit Sub

errorhandler:

    MsgBox Err.Description, vbExclamation, "Error Occurred", Err.HelpFile, Err.HelpContext

End Sub