AnsweredAssumed Answered

read Binary Format (FORMat REAL,32) with SICL

Question asked by overtheocean36 on Apr 4, 2011
Latest reply on Apr 5, 2011 by odanzy

Like • Show 0 Likes0
Comment • 5

Hi,

l'm trying to load IQ data from analyzer using raw GPIB command ( SICL)

to do so l use ( simplified):

iwrite (instance, "FORMat REAL,32",sizeof("FORMat REAL,32"),s,NULL);
iwrite (instance, "TRAC:IQ:DATA?",sizeof("TRAC:IQ:DATA?"),s,NULL);
iread (instance, strres, ss, NULL, &actual);

my understanding is the returedn data strres is a char * ..so how do l convert it to float ?

regards,

Michael

No one else has this question

Outcomes

5 Replies

odanzy Apr 5, 2011 1:00 AM
Mark Correct
Correct Answer
Depending on the language you are using? You can use either iscanf or ivscanf. Also, which instrument are you programming? These allow for formatted reads.
Like • Show 0 Likes0
Actions
overtheocean36 Apr 5, 2011 5:01 AM
Mark Correct
Correct Answer
I'm using C++ with Mingw on Windows.
Like • Show 0 Likes0
Actions
odanzy Apr 5, 2011 7:46 AM
Mark Correct
Correct Answer
The following code works for me using SICL on my PNA (network analyzer). It should give you at least a method to pursue. The bulk of what you would need is in the get_data function.

//This program uses the PNA and the SICL libraries to take a sweep and write
//the data to a file ('pna_data.txt'), along with the number of points and
//bytes returned. The data is returned in a binary 32-bit real format using the
//iscanf() function.
//
//This example program is provided on an as-is bases and carries no warrenty
//either written or implied. Use at your own risk.
//
//ojd 4.5.2011

#include <iostream>
#include <stdlib.h>
#include <fstream>
#include "sicl.h"

std::ofstream fout("pna_data.txt", std::ios::out);

//Function to select the trace for getting trace data and getting number of
//points that will be returned
unsigned long trace_select(INST vi)
{
    unsigned long points, cnt;
    char data[10];

    //Select default measurement as active measurement
    iwrite(vi,"CALC:PAR:SEL \'CH1_S11_1\'",24, 1, &cnt);

    //Set # of Points
    iwrite(vi, "SENS:SWE:POIN 201", 17, 1, &cnt);

    //Get Number of Points
    iwrite(vi, "SENS:SWE:POIN?", 14, 1, &cnt);
    iread(vi,data,10, 0, &cnt);
    points=atoi(data);

     //Write number of points to file
    fout<<"# of Points: "<<points<<std::endl;

    return points;
}

//Function to Get Trace Data from the PNA
void get_data(INST vi, unsigned long points)
{
    unsigned long cnt;
    long status;
    char opc_chk[3];
     long retcount;

    //use double instead of float if returning 64-bit floating point number
     float *data;

     retcount=points*2;

     data=(float *)malloc(points*4*2);

     //PNA Only
     /*Since we are reading back corrected data (SDATA) we will always receive 2 values back,
     if formatted data (FDATA) is selected, some formats only return 1 value. Please check the
     programmer's guide first if returning formatted data*/

    //Set Data return format to ASCII
     //use "FORM:DATA REAL,64" to return 64-bit floating numbers
    iwrite(vi,"FORM:DATA REAL,32",17, 1, &cnt);

    //Change sweep type to hold and take single sweep and wait for return
    iwrite(vi,"INIT:CONT OFF", 13, 1, &cnt);
    iwrite(vi, "INIT:IMM; *OPC?", 15, 1, &cnt);
    iread(vi,opc_chk, 5, 0, &cnt);

    //Query PNA for measurement data
    iwrite(vi,"CALC1:DATA? SDATA\n",18, 1, &cnt);

    //Read PNA Measurement data, use "%#Zb\n" if returning 64-bit floating point numbers
    status=iscanf(vi, "%#zb\n", &retcount, data);

     //Write Number of returned floats to screen
     std::cout<<"Element Return Count: "<<retcount<<std::endl;

    //Print results to File
    fout<<"Trace Data:"<<std::endl;

    //Format Trace Data in Real/Imaginary Pairs
    for(unsigned int i=0; i<points; ++i)
    {
        fout<<data[i*2]<<", "<<data[i*2+1]<<std::endl;
    }

    fout.close();
    std::cout<<"File Write Complete"<<std::endl;

    delete(data);
}

//Main function in the program
int main(int argc, char *argv[])
{
    //Declare variables
    INST vi;
    unsigned long cnt, points;
    char strret[100];
     long status;


    //Open Connection to PNA
    vi=iopen("gpib105,16");

    //Get identification string for PNA
    iwrite(vi, "*IDN?\n", 6, 1, &cnt);
    iread(vi, strret, 50, 0, &cnt);
    strret[cnt]='\0';
    fout<<"PNA Identification: "<<strret;

    //Preset the analyzer & Wait for complete
    iwrite(vi, "SYST:PRES; *OPC?\n",17, 1, &cnt);
    iread(vi, strret, 5, 0, &cnt);
    strret[cnt]='\0';
    std::cout<<"Preset Complete"<<std::endl;

    //Execute Trace Select Function
    points=trace_select(vi);

    //Execute Get Data function
    get_data(vi, points);

     iclose(vi);

    return 0;
}
Like • Show 0 Likes0
Actions
overtheocean36 Apr 5, 2011 8:43 AM
Mark Correct
Correct Answer
this is exactly what l was looking for ...

last question: to read ASCII data with "\n" in it ... what should be the filter to preserve this \n ?

regards,

Michael
Like • Show 0 Likes0
Actions
odanzy Apr 5, 2011 9:06 AM
Mark Correct
Correct Answer
I've never tried this, but you could try setting the termination character (using itermchr) to -1 and see if that works. This means that the reads will only end if the maximum number of bytes are read or if a END is received. Most people I've worked with want to get rid of the newline character.
Like • Show 0 Likes0
Actions

read Binary Format (FORMat REAL,32) with SICL

Outcomes

Related Content

Recommended Content