trouble select between Differential and RSE

[rjohnson]

I can measure a differential DC signal using Labwindows/CVI, but I can not measure a ground RSE signal using same.

it works correctly using MAX, where i can select the terminal configuration between differential and RSE as necessary, but i cant get my Labwindows/CVI application to work correctly.  It wants to treat all analog input measurements as differential signals.

thanks in advance for any assistance.

[WM_John_Weeks]

You must have one or more calls to DAQmxCreateAIVoltageChan() (or the equivalent for Labwindows/CVI). That's where the input configuration is set. Show us the call as it appears in your code.

Also- what kind of DAQ device are you using?

[rjohnson]

i guess i'm missing something fundamental.    ive tried a variety of methods; below is excerpt of what i have now.  thanks for your help.



static TaskHandle taskHandle6=0;

int main (int argc, char *argv[])
{

    int channelnumber=0;
   
    if (InitCVIRTE (0, argv, 0) == 0)
        return -1;    /* out of memory */
    if ((panelHandle = LoadPanel (0, "test2.uir", PANEL)) < 0)
        return -1;
   
    DAQmxCreateAIVoltageChan (taskHandle6, "Dev1/ai6", "DUT55C", DAQmx_Val_RSE, -10.0,
                              10.0, DAQmx_Val_Volts, NULL);

    DisplayPanel (panelHandle);
    InitializeSettings ();
    RunUserInterface ();
    DiscardPanel (panelHandle);
    return 0;
}


int CVICALLBACK DoVoltTest (int panel, int control, int event,
        void *callbackData, int eventData1, int eventData2)
{
    int32            error=0;
    int                a;
    char            chan[256];
    float64        value;
    char            errBuff[2048]={'\0'};

     
    if( event==EVENT_COMMIT )
    {

        DAQmxErrChk (Configure_AcqOneSample("DUT55C",0,10,&taskHandle6));
        DAQmxErrChk (Start_AcqOneSample(taskHandle6));
        DAQmxErrChk (Read_AcqOneSample(taskHandle6,&value));

        SetCtrlVal(panel,PANEL_VTEST_6,value);

    }
  

Error:       
    ErrorCheck (error, errBuff, taskHandle6, 3);  
   
    return 0;
   
}

[rjohnson]

oh, and i'm using a NI-DAQmx 6251

if you could just tell me where some examples using this function are, that would probably be just fine.  I seem to be having a rough time sorting through the documentation and examples.

thanks

--Rob

[rjohnson]

d'oh.

found my problem.    yes, i was missing something very fundamental.

please delete this entire post and hide the evidence of my ignorance.