Create a Measurement and Read Data

// This example demonstrates how to use C# to communicate with Keysight VNA
// The example demonstrates using helper function to check for all possible errors
// during the running of the code. Checking for errors helps identify problems early


// Add visa32.cs to the project.
// It it is here (after installing IO Libraries on your PC)
// C:\Program Files\IVI Foundation\VISA\Win64\agvisa\include\agvisa32.cs

using System;
using System.Text;

class BasicCSharp
{

    // Variables to store the VISA session numbers
    static int g_defaultSession = -1;
    static int g_session = -1;

    static void Main(string[] args)

    {
        try
        {
            // Find the VISA address from the SCPI parser console on your VNA
            // System->System Setup->Remote Interface... Show SCPI parser Console -> Status
            // TODO: CHANGE THIS VISA_ADDRESS to point to your VNA
            string VISA_ADDRESS = "TCPIP0::localhost::hislip0::INSTR";
            int timeout = 1000;

            CheckViStatus(visa32.viOpenDefaultRM(out g_defaultSession));
            CheckViStatus(visa32.viOpen(g_defaultSession, VISA_ADDRESS, 0, timeout, out g_session));
            CheckViStatus(visa32.viSetAttribute(g_session, visa32.VI_ATTR_TMO_VALUE, timeout));

            // Destroy all measurements and add a window
            WriteString("SYST:FPR");
            WriteString("DISP:WIND:STAT 1");

            // Check for any SCPI errors that occurred
            CheckForErrors();

            // Create S11 measurement.
            // HINT(optional): SCPI commands can use single quotes to delineate strings. It is easier than escaping double quotes
            WriteString("CALC1:MEAS1:DEF 'S11'");

            // Displays measurement 1 in window 1 and assigns the next available trace number to the measurement
            WriteString("DISP:MEAS1:FEED 1");

            // Put the channel in hold mode - good idea for fast setup
            WriteString("SENS1:SWEep:MODE HOLD");

            // Change point count to 51
            int pointCount = 51;
            WriteString($"SENS1:SWEep:POINts {pointCount}");

            // Change start frequency to 1 GHz and stop to 2 GHz
            WriteString("SENS1:FREQuency:STARt 1e9");
            WriteString("SENS1:FREQuency:STOP 2e9");

            // Check for any SCPI errors that occurred
            CheckForErrors();

            // Take a sweep
            WriteString("SENS1:SWE:MODE SING");

            // Check for any SCPI errors that occurred
            CheckForErrors();

            // Block until the sweep is complete. *OPC? is used to block on any asynchronous (overlapped) operation
            // If the sweep is slow, then this could block for a long time
            Query("*OPC?");

            float[] traceData = QueryFloatArray("CALC1:MEAS:DATA:FDATa?",pointCount);

            for (int i=0;i<traceData.Length;i++)
            {
                Console.Write(traceData[i]);
                if (i != traceData.Length - 1)
                    Console.Write(",");
            }
            Console.WriteLine(); // newline
            Console.WriteLine("Success!");
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error occurred:" +  ex.Message);
        }

        // Close the handles - even if there was an error
        if (g_session != -1)
            visa32.viClose(g_session);
        if (g_defaultSession != -1)
            visa32.viClose(g_defaultSession);
    }

    // Helper function to write a string. Automatically adds the newline
    static void WriteString(string command)
    {
        command += "\n";
        CheckViStatus(visa32.viPrintf(g_session, command));
        CheckForErrors();
    }

    // Helper function to query a string
    static string Query(string query)
    {
        query += "\n";
        CheckViStatus(visa32.viPrintf(g_session, query));
        StringBuilder errorMessage = new StringBuilder();
        CheckViStatus(visa32.viScanf(g_session, "%t", errorMessage));
        return errorMessage.ToString();
    }

    // Helper function to query an array of floats
    static float[] QueryFloatArray(string query,int expectedSize)
    {
        query += "\n";
        float[] myArray = new float[expectedSize];
        // Read the formatted data
        CheckViStatus(visa32.viPrintf(g_session,query));
        int pointCountIn = expectedSize;

        // viScanF automatically breaks apart comma separated values into the given array
        CheckViStatus(visa32.viScanf(g_session, "%,#f", ref pointCountIn, myArray));
        if (pointCountIn != expectedSize)
            throw new Exception("Point Count read does not match");
        return myArray;
    }


    // Helper function to check for any error with a VISA call
    static void CheckViStatus(int viStatus)
    {
        if (viStatus < 0) // If the viStatus is less than 0, then it indicates an error
        {
            // Convert the error number to a string
            StringBuilder errorMessage = new StringBuilder();
            visa32.viStatusDesc(g_session, viStatus, errorMessage);

            // Throw an exception with the string
            throw new Exception(errorMessage.ToString());
        }
    }

    // Helper function to check for logical SCPI errors
    static void CheckForErrors()
    {
        // First check if there was a SCPI error
        CheckViStatus(visa32.viPrintf(g_session, "SYST:ERR:COUN?\n"));
        int errorCount;
        CheckViStatus(visa32.viScanf(g_session, "%d", out errorCount));
        if (errorCount == 0)
            return; // no errors

        // There is an error, let's convert it to a string
        StringBuilder allErrors = new StringBuilder();
        for (int i = 0; i < errorCount; i++)
        {
            CheckViStatus(visa32.viPrintf(g_session, "SYST:ERR?\n"));
            StringBuilder errorMessage = new StringBuilder();
            CheckViStatus(visa32.viScanf(g_session, "%t", errorMessage));
            allErrors.Append(errorMessage);
        }
        throw new Exception(allErrors.ToString());
    }

}