Measurementproblems with NI USB-6008 in Visual C++ 6.0

Question

Hi,
I'm trying to read some data from this device, but I'm sill in trouble
with it. With this code I get a few values, but then I get the
following error:
DAQmx Error: Attempted to read samples that are no longer available.
The requested sample was previously available, but has since been
overwritten.
Increasing the buffer size, reading the data more frequently, or
specifying a fixed number of samples to read instead of reading all
available samples might correct the problem.
Property: DAQmx_Read_RelativeTo
Corresponding Value: DAQmx_Val_CurrReadPos
Property: DAQmx_Read_Offset
Corresponding Value:
Task Name: _unnamedTask<0>
Status Code: -200279
Maybe someone could have a look in my sourcecode:
#define DAQmxErrChk(functionCall) if( DAQmxFailed(error=(functionCall)) ) goto Error; else
THardwareInterface::THardwareInterface(int dev)
    // Task parameters
    taskHandle = 0;
    char        chan[10];
    sprintf(chan,"Dev%d/ai0:7",dev);
    float64     min = -10.0;
    float64     max = 10.0;
    // Timing parameters
    char        clockSource[] = "OnboardClock";
    uInt64      samplesPerChan = 1;
    float64     sampleRate = 1000;
    DAQmxCreateTask("",&taskHandle);
    DAQmxCreateAIVoltageChan(taskHandle, chan, "", DAQmx_Val_RSE, min, max, DAQmx_Val_Volts, NULL);
    DAQmxCfgSampClkTiming(taskHandle, clockSource,
sampleRate, DAQmx_Val_Rising, DAQmx_Val_ContSamps, samplesPerChan);
    DAQmxCfgInputBuffer(taskHandle,7);
    DAQmxStartTask(taskHandle);
unsigned short THardwareInterface::readValue(int kNr)
    // Data read parameters
    short        data[KANALANZAHL + 1];
    int32       pointsToRead = 1;
    int32       pointsRead;
    float64     timeout = 10.0;
    int32       totalRead = 0;
    unsigned short value;
    int32       error = 0;
    char    errBuff[2048]={'\0'};
    DAQmxErrChk
(DAQmxReadBinaryU16(taskHandle,pointsToRead,timeout,DAQmx_Val_GroupByScanNumber,data,KANALANZAHL,&pointsRead,NULL));
    value=(data[kNr-1]);
    return value >> 5;
Error:
    if( DAQmxFailed(error) ) {
        DAQmxGetExtendedErrorInfo(errBuff,2048);
        DAQmxClearTask(taskHandle);
    return -1;
Thanks, SWT

Answer 1

And here the sourcecode:
// cpp Datein zur Headerdatei THardwareInterface.h
#include "THardwareInterface.h"
#include <time.h>
#include <iostream>
#include <stdlib.h>
#include <string>
#include <NIDAQmx.h>
using namespace std;
THardwareInterface& THardwareInterface::exemplar(int dev)
    static THardwareInterface instanz(dev);
    return instanz;
THardwareInterface::THardwareInterface(int dev)
    // Task parameters
    taskHandle = 0;
    char        chan[10];
    sprintf(chan,"Dev%d/ai0:7",dev);
    float64     min = -10.0;
    float64     max = 10.0;
    // Timing parameters
    char        clockSource[] = "";
    uInt64      samplesPerChan = 2;
    float64     sampleRate = 1000;
    DAQmxCreateTask("",&taskHandle);
    DAQmxCreateAIVoltageChan(taskHandle,chan,"",DAQmx_Val_RSE,min,max,DAQmx_Val_Volts,NULL);
    DAQmxCfgSampClkTiming(taskHandle,NULL,sampleRate,DAQmx_Val_Rising,DAQmx_Val_FiniteSamps,samplesPerChan);
    fehlerZaehler = 0;
    ausdatei.open("error_log.txt");
THardwareInterface::~THardwareInterface()
    ausdatei.close();
bool THardwareInterface::liesWerte()
    // Data read parameters
    int32            pointsToRead = 1;
    int32            pointsRead;
    float64            timeout = 0.5;
    int32            error = 0;
    char            errBuff[2048]={'\0'};
    SYSTEMTIME*        sysTime = 0;
    fehlerZaehler++;
    DAQmxStartTask(taskHandle);
    DAQmxErrChk
(DAQmxReadBinaryU16(taskHandle,pointsToRead,timeout,DAQmx_Val_GroupByScanNumber,data,KANALANZAHL,&pointsRead,NULL));
    DAQmxStopTask(taskHandle);
    fehlerZaehler = 0;
    return true;
Error:
    if( DAQmxFailed(error) ) {
        DAQmxGetExtendedErrorInfo(errBuff,2048);
        sysTime = new SYSTEMTIME;
        GetLocalTime(sysTime);
        ausdatei <<
sysTime->wDay << "." << sysTime->wMonth << "."
<< sysTime->wYear << " "
     << sysTime->wHour << ":"
<< sysTime->wMinute << ":" << sysTime->wSecond
<< endl;
        delete sysTime;
        ausdatei << "DAQmx Error: "
<< errBuff << endl << endl << endl;
    if (fehlerZaehler <= 5)
        return liesWerte();
    else {
        fehlerZaehler = 0;
        return false;
unsigned short THardwareInterface::gibWert(int kNr)
    unsigned short    wert;
    wert=(data[kNr-1]);
    return wert >> 5;