ECALConfidence Check using SCPI

This Visual Basic program performs a complete ECAL confidence check.

To run this program, you need:

• An established GPIB interface connection

• Keysight's VISA or National Instrument's VISA installed on your PC

• The module visa32.bas added to your VB project.

• A form with two buttons: cmdRun and cmdQuit

• A calibrated S11 1-port or N-port measurement active on Channel 1

• Window 1 is visible

Note: A confidence check can NOT be performed remotely from User Characterizations that are stored on the PNA disk.

See Other SCPI Example Programs

'Session to VISA Default Resource Manager

Private defRM As Long            

'Session to PNA

Private viPNA As Long             

'VISA function status return code

Private status As Long            

Private Sub Form_Load()

   defRM = 0

End Sub

Private Sub cmdRun_Click()

'String to receive data from the PNA

Dim strReply As String * 200  

' Open the VISA default resource manager

status = viOpenDefaultRM(defRM)

If (status < VI_SUCCESS) Then HandleVISAError

' Open a VISA session (viPNA) to the PNA at GPIB address 16.

status = viOpen(defRM, "GPIB0::16::INSTR", 0, 0, viPNA)

If (status < VI_SUCCESS) Then HandleVISAError

' Need to set the VISA timeout value to give all our GPIB Reads

' sufficient time to complete before a timeout error occurs.

' For this example, let's try setting the limit to

' 10000 milliseconds (10 seconds).

status = viSetAttribute(viPNA, VI_ATTR_TMO_VALUE, 10000)

If (status < VI_SUCCESS) Then HandleVISAError

' Get the catalog of all the measurements currently on Channel 1.

status = myGPIBWrite(viPNA, "CALC1:PAR:CAT?")

If (status < VI_SUCCESS) Then HandleVISAError

status = myGPIBRead(viPNA, strReply)

If (status < VI_SUCCESS) Then HandleVISAError

' If an S11 measurement named "MY_S11" doesn't already exist,

' then create it.

If InStr(strReply, "MY_S11") = 0 Then

   status = myGPIBWrite(viPNA, "CALC1:PAR:DEF:EXT MY_S11,S11")

   If (status < VI_SUCCESS) Then HandleVISAError

End If

strReply = ""

' Get the catalog of all the trace numbers currently active

' in Window 1.

status = myGPIBWrite(viPNA, "DISP:WIND1:CAT?")

If (status < VI_SUCCESS) Then HandleVISAError
 

status = myGPIBRead(viPNA, strReply)

If (status < VI_SUCCESS) Then HandleVISAError

' If a trace number 4 already exists in Window 1, then this

' will remove it.

If InStr(strReply, "4") > 0 Then

   status = myGPIBWrite(viPNA, "DISP:WIND1:TRAC4:DEL")

   If (status < VI_SUCCESS) Then HandleVISAError

End If

' Set trace number 4 to MY_S11.

status = myGPIBWrite(viPNA, "DISP:WIND1:TRAC4:FEED MY_S11")

If (status < VI_SUCCESS) Then HandleVISAError

' Set up trace view so we are viewing only the data trace.

status = myGPIBWrite(viPNA, "DISP:WIND1:TRAC4 ON")

If (status < VI_SUCCESS) Then HandleVISAError

status = myGPIBWrite(viPNA, "DISP:WIND1:TRAC4:MEM OFF")

If (status < VI_SUCCESS) Then HandleVISAError

' Select MY_S11 as the measurement to be used for the

' Confidence Check.

status = myGPIBWrite(viPNA, "SENS1:CORR:CCH:PAR MY_S11")

If (status < VI_SUCCESS) Then HandleVISAError

' Acquire the S11 confidence check data from ECal Module A

' into the memory buffer (asking for an OPC reply when it's done).

status = myGPIBWrite(viPNA, "SENS1:CORR:CCH:ACQ ECAL1;*OPC?")

If (status < VI_SUCCESS) Then HandleVISAError

' The PNA sends an OPC reply ("+1") when the confidence data

' acquisition into memory is complete, so this Read is waiting on

' the reply until it is received.

status = myGPIBRead(viPNA, strReply)

If (status < VI_SUCCESS) Then HandleVISAError

' Turn on trace math so the trace shows data divided by memory.

' You can be confident the S11 calibration is reasonably good if

' the displayed trace varies no more than a few tenths of a dB

' from 0 dB across the entire span.

status = myGPIBWrite(viPNA, "CALC1:PAR:SEL MY_S11")

If (status < VI_SUCCESS) Then HandleVISAError

status = myGPIBWrite(viPNA, "CALC1:MATH:FUNC DIV")

If (status < VI_SUCCESS) Then HandleVISAError

End Sub

Private Sub cmdQuit_Click()

' Turn off trace math

status = myGPIBWrite(viPNA, "CALC1:MATH:FUNC NORM")

If (status < VI_SUCCESS) Then HandleVISAError

' Conclude the confidence check to set the ECal module

' back to it's idle state.

status = myGPIBWrite(viPNA, "SENS1:CORR:CCH:DONE")

If (status < VI_SUCCESS) Then HandleVISAError

' Close the resource manager session (which also closes

' the session to the PNA).

If defRM <> 0 Then Call viClose(defRM)

' End the program

End

End Sub

Private Function myGPIBWrite(ByVal viHandle As Long, ByVal strOut As String) As Long

' The "+ Chr$(10)" appends an ASCII linefeed character to the output, for

' terminating the write transaction.

myGPIBWrite = viVPrintf(viHandle, strOut + Chr$(10), 0)

End Function

Private Function myGPIBRead(ByVal viHandle As Long, strIn As String) As Long

myGPIBRead = viVScanf(viHandle, "%t", strIn)

End Function

Sub HandleVISAError()

Dim strVisaErr As String * 200

Call viStatusDesc(defRM, status, strVisaErr)

MsgBox "*** Error : " + strVisaErr, vbExclamation

End

End Sub