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read data NI USB 6008 python

Hi,

     

       I have problem when I call the NI USB 6008 read function in Python script. 

I implement the read function in C++ and the function is verified in C++. When I call the read function in python script, the read function always outputs the initial value which is 0.0 . I use swig between python and C++.

 

 

C++ code of the reading function:

 void DAQAIRead::read()
{
    mlString    task( "AITask" );

    TaskHandle  handle;

    // Channel parameters
    char        chan[] = "Dev1/ai0";
    float64     min = -10.0;
    float64     max = 10.0;

    // Timing parameters
    uInt64      samplesPerChan = 1;

    // Data read parameters
    float64     data=0.0;
    int32       pointsToRead = 1;
    int32       pointsRead;
    float64     timeout = 10.0;
    int32       nrSamps=0;

    int32 rv =0;
    // Init
    rv = DAQmxBaseCreateTask( task.c_str(), &handle );

    cout<<"DAQmxBaseCreateTask:handle:"<<handle<<endl<<"&handle"<<&handle<<endl;

    rv = DAQmxBaseCreateAIVoltageChan(handle,"Dev1/ai0","",DAQmx_Val_Cfg_Default,min,max,DAQmx_Val_Volts,0);


    rv = DAQmxBaseStartTask(handle);


    rv = DAQmxBaseReadAnalogF64(handle,DAQmx_Val_Auto,10.0,DAQmx_Val_GroupByChannel,&data,1,&nrSamps,0);


    rv =  DAQmxBaseStopTask(handle);


    cout<<"data :"<<data<<endl;

}

 

I get correct data value by calling from C++. If I call this function from Python script. I always get 0.0 which is the initial value of data.

 

Is there anyone has similiar problem and would like to share your idea about how to solve it?

 

Thank you!!

 

 

 

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Message 1 of 2
(3,667 Views)

Hi Feiteng,

 

Officially NI does not support questions regarding Python. However, NI provides some information on how to program NI DAQmx applications using Python.

 

Please take a look at the following webpage.

 

There you will find some instructions.

 

I hope this will provide you with a working solution.

 

Best regards,

Peter S

 

 

 

Message 2 of 2
(3,600 Views)