System halts after viEnableEvent()

[hauke webermann]

Hello,

after I'm calling the function viEnableEvent my System (x86 Realtime target) halts and no connection via Labview, Web, FTP is possible.

Here is my code in CVI:

#include <utility.h>
#include <ansi_c.h>
#include <cvirte.h>
#include <visa.h>

int  __stdcall InitLibrary(void);

ViStatus _VI_FUNCH IntrHandler(ViSession vi, ViEventType eventType, ViEvent context, ViAddr userhandle)
{
	printf("An event was received.\n");
	return VI_SUCCESS;
}

int __stdcall DllMain (HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
	switch (fdwReason)
	{
		case DLL_PROCESS_ATTACH:
			if (InitCVIRTE (hinstDLL, 0, 0) == 0)
				return 0;	  /* out of memory */
			InitLibrary();
			break;
		case DLL_PROCESS_DETACH:
			CloseCVIRTE ();
			break;
	}
	return 1;
}

ViSession defaultRM;
ViSession session;

int __stdcall InitLibrary(void)
{
	ViStatus status; 

	status = viOpenDefaultRM (&defaultRM);
	if (status < VI_SUCCESS) {
		printf("Could not open a session to the VISA Resource Manager!\n");
		return 0;
	}  
 
	status = viFindRsrc(defaultRM, "PXI?*INSTR{VI_ATTR_MANF_ID==0x1234 && VI_ATTR_MODEL_CODE==0x1234}", &findList, &numInstrs, instrDescriptor);
	if (status < VI_SUCCESS){
		printf ("An error occurred while finding resources.\n");
		return status;
	}

	status = viOpen(defaultRM, instrDescriptor, VI_NULL, VI_NULL, &session);
	if (status < VI_SUCCESS) {
		printf ("An error occurred opening a session to %s\n",instrDescriptor);
		return status;
	}

	status = viInstallHandler(session, VI_EVENT_PXI_INTR, IntrHandler, VI_NULL);
	if (status < VI_SUCCESS) {
		printf("Could not install the interrupt handler.\n");
		viClose (defaultRM);
		return -1;          
	}
	printf("Installed the interrupt handler.\n");

	status = viEnableEvent(session, VI_EVENT_PXI_INTR, VI_HNDLR, VI_NULL); 
/// MY SYSTEM STOPPED HERE!
	if (status < VI_SUCCESS) {
		printf("Could not enable the interrupt event (0x%x).\n", status);
		viClose (defaultRM);
		return -1;          
	}
	printf("Enabled the interrupt event.\n");

        return 1;
}

If I replace VI_HNDLR to VI_QUEUE, the program continues.

With the Driver Wizard I already generated an inf File for my hardware. I also communicated correcly with my card.

Does anyone know what condition(s) can cause this error or know what the problem may be?

Thanks,

Hauke

[hauke webermann]

Hello,

after I'm calling the function viEnableEvent my System (x86 Realtime target) halts and no connection via Labview, Web, FTP is possible.

Here is my code in CVI:

#include <utility.h>
#include <ansi_c.h>
#include <cvirte.h>
#include <visa.h>

int  __stdcall InitLibrary(void);

ViStatus _VI_FUNCH IntrHandler(ViSession vi, ViEventType eventType, ViEvent context, ViAddr userhandle)
{
	printf("An event was received.\n");
	return VI_SUCCESS;
}

int __stdcall DllMain (HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
	switch (fdwReason)
	{
		case DLL_PROCESS_ATTACH:
			if (InitCVIRTE (hinstDLL, 0, 0) == 0)
				return 0;	  /* out of memory */
			InitLibrary();
			break;
		case DLL_PROCESS_DETACH:
			CloseCVIRTE ();
			break;
	}
	return 1;
}

ViSession defaultRM;
ViSession session;

int __stdcall InitLibrary(void)
{
	ViStatus status; 

	status = viOpenDefaultRM (&defaultRM);
	if (status < VI_SUCCESS) {
		printf("Could not open a session to the VISA Resource Manager!\n");
		return 0;
	}  
 
	status = viFindRsrc(defaultRM, "PXI?*INSTR{VI_ATTR_MANF_ID==0x1234 && VI_ATTR_MODEL_CODE==0x1234}", &findList, &numInstrs, instrDescriptor);
	if (status < VI_SUCCESS){
		printf ("An error occurred while finding resources.\n");
		return status;
	}

	status = viOpen(defaultRM, instrDescriptor, VI_NULL, VI_NULL, &session);
	if (status < VI_SUCCESS) {
		printf ("An error occurred opening a session to %s\n",instrDescriptor);
		return status;
	}

	status = viInstallHandler(session, VI_EVENT_PXI_INTR, IntrHandler, VI_NULL);
	if (status < VI_SUCCESS) {
		printf("Could not install the interrupt handler.\n");
		viClose (defaultRM);
		return -1;          
	}
	printf("Installed the interrupt handler.\n");

	status = viEnableEvent(session, VI_EVENT_PXI_INTR, VI_HNDLR, VI_NULL); 
/// MY SYSTEM STOPPED HERE!
	if (status < VI_SUCCESS) {
		printf("Could not enable the interrupt event (0x%x).\n", status);
		viClose (defaultRM);
		return -1;          
	}
	printf("Enabled the interrupt event.\n");

        return 1;
}

If I replace VI_HNDLR to VI_QUEUE, the program continues.

With the Driver Wizard I already generated an inf File for my hardware. I also communicated correcly with my card.

Does anyone know what condition(s) can cause this error or know what the problem may be?

[hauke webermann]

I already wrote that when I call the function viEnableEvent with the parameter VI_QUEUE, the event is attached.

If I activate VI_QUEUE and VI_HNDLR like:

viEnableEvent(session, VI_EVENT_PXI_INTR, VI_QUEUE|VI_HNDLR, VI_NULL);

I get an error code BFFF00A4h (VI_ERROR_NSUP_MECH, The specified mechanism is not supported by the given event type.) and the RT target restarts automatically after 2 seconds.

Maybe this information will help...

Thanks

Hauke Webermann

[hauke webermann · Accepted solution]

When the DLLMain thread call viEnableEvent, I think it is created a special thread with the event handler function and the DLLMain thread suspends on a condition or semaphore. So the main thread waits for the new thread is started. The new thread sends an event or a signal to the DLLMain thread and wakes it up. But I called the viEnableEvent in my initialization in the DLLMain during DLL_PROCESS_ATTACH. During this time no other threads can run and so the main thread waits for a thread which can’t start.

As a solution I have now created a thread that’s starts even after the initialization process and initialize the interrupt event.