NI 9401, Error Code -200022: Resource requested already reserved

[whemdan]

Hi,

I am trying to use the NI 9401 in an NI cDAQ-9174 to do both digital input and output reads and writes.

I am using the following code, and added calls to unreserve the channels after using them - but I still get the -200022 failure.

Thanks,

   Wael Hemdan

   MathWorks

#include <stdio.h>
#include <NIDAQmx.h>

#define DAQmxErrChk(functionCall) if( DAQmxFailed(error=(functionCall)) ) goto Error; else

int main(void)
{
	int         error=0;
        TaskHandle  taskHandleDI=0;
        TaskHandle  taskHandleDO=0;
	uInt8       data;
	char        errBuff[2048]={'\0'};

	/*********************************************/
	// DAQmx Configure Code
	/*********************************************/
	DAQmxErrChk (DAQmxCreateTask("",&taskHandleDI));
        DAQmxErrChk (DAQmxCreateTask("",&taskHandleDO));

	DAQmxErrChk (DAQmxCreateDIChan(taskHandleDI,"cdaq1mod1/port0/line0","",DAQmx_Val_ChanForAllLines));
        DAQmxErrChk (DAQmxCreateDIChan(taskHandleDI,"cdaq1mod1/port0/line1","",DAQmx_Val_ChanForAllLines));
        DAQmxErrChk (DAQmxCreateDIChan(taskHandleDI,"cdaq1mod1/port0/line2","",DAQmx_Val_ChanForAllLines));
        DAQmxErrChk (DAQmxCreateDIChan(taskHandleDI,"cdaq1mod1/port0/line3","",DAQmx_Val_ChanForAllLines));

        DAQmxErrChk (DAQmxCreateDOChan(taskHandleDO,"cdaq1mod1/port0/line4","",DAQmx_Val_ChanForAllLines));
        DAQmxErrChk (DAQmxCreateDOChan(taskHandleDO,"cdaq1mod1/port0/line5","",DAQmx_Val_ChanForAllLines));
        DAQmxErrChk (DAQmxCreateDOChan(taskHandleDO,"cdaq1mod1/port0/line6","",DAQmx_Val_ChanForAllLines));
        DAQmxErrChk (DAQmxCreateDOChan(taskHandleDO,"cdaq1mod1/port0/line7","",DAQmx_Val_ChanForAllLines));

	/*********************************************/
	// DAQmx Start Code
	/*********************************************/
	DAQmxErrChk (DAQmxStartTask(taskHandleDI));
        DAQmxErrChk (DAQmxStartTask(taskHandleDO));

	printf("Continuously polling. Press Ctrl+C to interrupt\n");
	while( 1 ) {
            /*********************************************/
	    // DAQmx Read Code
	    /*********************************************/
            DAQmxErrChk (DAQmxTaskControl(taskHandleDI, DAQmx_Val_Task_Commit));
            DAQmxErrChk (DAQmxReadDigitalLines(taskHandleDI,1,10,DAQmx_Val_GroupByScanNumber,&data,2048,0,0,0));
            DAQmxErrChk (DAQmxTaskControl(taskHandleDI, DAQmx_Val_Task_Unreserve));

            DAQmxErrChk (DAQmxTaskControl(taskHandleDO, DAQmx_Val_Task_Commit));
            DAQmxErrChk (DAQmxWriteDigitalLines(taskHandleDO,1,1,10,DAQmx_Val_GroupByScanNumber,&data,0,0));
            DAQmxErrChk (DAQmxTaskControl(taskHandleDO, DAQmx_Val_Task_Commit));

	    printf("\rCount: %d",data);
	    fflush(stdout);
	}

Error:
	puts("");
	if( DAQmxFailed(error) )
		DAQmxGetExtendedErrorInfo(errBuff,2048);
	if(( taskHandleDI!=0 ) && (taskHandleDO!=0)) {
		/*********************************************/
		// DAQmx Stop Code
		/*********************************************/
		DAQmxStopTask(taskHandleDI);
        DAQmxStopTask(taskHandleDO);
        DAQmxClearTask(taskHandleDI);
		DAQmxClearTask(taskHandleDO);
	}
	if( DAQmxFailed(error) )
		printf("DAQmx Error: %s\n",errBuff);
	printf("End of program, press Enter key to quit\n");
	getchar();
	return 0;
}

 
DAQmx Error: Resource requested by this task has already been reserved by a different task.
Device: cDAQ1Mod1

Task Name: _unnamedTask<0>

Status Code: -200022
End of program, press Enter key to quit

[MarkGrot]

Hi Wael,

Did you check where the code errors?  I bet it's the second start.  The reserves need to happen before any task is started.

I think what you're trying to do is something like this:

DI reserve

DO reserve

DI start

DO start

while loop

  DI read

  DO write

DI stop

DO stop

DI clear

DO clear