Can't get data using C++ API from NI-PCI 6225 card

[soheil08]

Hi all,

Thanks to NIDAQmx.h library and the related samples, I’ve developed a simple C++ program which was working perfectly until I was forced to reinstall the same Operating System, particularly Centos 7 as the first time. 

I installed all the drivers and packages just like before and checked “nilsdev —verbose” command which returns the device name correctly. Unfortunately, now my code just runs till “DAQmxErrChk (DAQmxStartTask(taskHandle));” and after that just will stick in an infinite loop without any trying to run callbackFunction. Finally, I should stop the whole C++  program to exit.

How can I solve the problem?

Best regards

int main(void)
{
int32       error=0;
char        errBuff[2048]={'\0'};

/*********************************************/
// DAQmx Configure Code
/*********************************************/
DAQmxErrChk (DAQmxCreateTask("",&taskHandle));
DAQmxErrChk (DAQmxCreateDIChan(taskHandle,"Dev1/port0/line0:7","",DAQmx_Val_ChanPerLine));
DAQmxErrChk (DAQmxCfgChangeDetectionTiming(taskHandle,"Dev1/port0/line0:7","Dev1/port0/line0:7",DAQmx_Val_ContSamps,1));
DAQmxErrChk (DAQmxRegisterSignalEvent(taskHandle,DAQmx_Val_ChangeDetectionEvent,0,ChangeDetectionCallback,NULL));
DAQmxErrChk (DAQmxGetTaskNumChans(taskHandle,&numLines));

/*********************************************/
// DAQmx Start Code
/*********************************************/
DAQmxErrChk (DAQmxStartTask(taskHandle));

puts("Continuously reading. Press Enter key to interrupt\n");

puts("Timestamp                 Data read   Changed Lines");

getchar();

Error:
if( DAQmxFailed(error) )
{
    DAQmxGetExtendedErrorInfo(errBuff,2048);
    Cleanup();
    printf("DAQmx Error: %s\n",errBuff);
}
printf("End of program, press Enter key to quit\n");
getchar();
return 0;
}

int32 CVICALLBACK ChangeDetectionCallback(TaskHandle taskHandle, int32 signalID, void *callbackData)
{
int32   error=0;
uInt8   data[200]={0};
int32   numRead;
uInt32  i=0;
char    buff[512], *buffPtr;
char    errBuff[2048]={'\0'};
char    *timeStr;
time_t  currTime;

if( taskHandle ) {
    time (&currTime);
    timeStr = ctime(&currTime);
    timeStr[strlen(timeStr)-1]='\0';  // Remove trailing newline.

    /*********************************************/
    // DAQmx Read Code
    /*********************************************/
    DAQmxErrChk (DAQmxReadDigitalLines(taskHandle,1,10.0,DAQmx_Val_GroupByScanNumber,data,8,&numRead,NULL,NULL));

    if( numRead ) {
        buffPtr = buff;
        strcpy(buff, timeStr);

        strcat(buff,"  ");
        buffPtr = buff + strlen(buff);
        for(;i<numLines;++i) {
            sprintf(buffPtr,"%d",data[i]);
            buffPtr++;
        }

        strcat(buff,"    ");
        buffPtr = buff + strlen(buff);
        for(i=0;i<numLines;++i) {
            sprintf(buffPtr,"%c",data[i]==cachedData[i]?'-':'X');
            buffPtr++;
            cachedData[i] = data[i];
        }
        puts(buff);
        fflush(stdout);
    }
}
return 0;

Error:
if( DAQmxFailed(error) )
{
    DAQmxGetExtendedErrorInfo(errBuff,2048);
    Cleanup();
    printf("DAQmx Error: %s\n",errBuff);
}
return 0;
}

void Cleanup (void)
{
if( taskHandle!=0 ) 
{
    /*********************************************/
    // DAQmx Stop Code
    /*********************************************/
    DAQmxStopTask(taskHandle);
    DAQmxClearTask(taskHandle);
    taskHandle = 0;
}
}