Hi,
I have been looking for some information about PXI and interruptions but there is not too much information online, so I am a little bit lost. I have to develop a program to detect an interruption from a PXI and then retrieve the data from third part 3 part device that some colleagues have developed. To start, I modified a little bit the example that the VISA driver includes in its help (I just changed the event from the original file).
#include <stdio.h>
#include <stdlib.h>
#include "visa.h"
static ViUInt16 StatusID;
static ViSession instr;
static ViSession defaultRM;
static ViStatus status;
static int tempchar;
ViStatus _VI_FUNCH IntrHandler(ViSession instr, ViEventType etype, ViEvent event, ViAddr userhandle);
/*
* Here we define the function that is called whenever an interrupt event is received. */
ViStatus _VI_FUNCH IntrHandler(ViSession instr, ViEventType etype, ViEvent event, ViAddr userhandle)
{
/* etype is a number which identifies the event type that has been received. */
viGetAttribute (event, VI_ATTR_SIGP_STATUS_ID, &StatusID);
printf("An event was received. The Status/ID value is 0x%x\n",StatusID);
/* System calls are allowed to be used inside the event handler on all VISA supported platforms other than Macintosh. */
return VI_SUCCESS;
}
int main (void)
{
/*First we must call viOpenDefaultRM to get the manager handle. We will store this handle in defaultRM. */
status=viOpenDefaultRM (&defaultRM);
if (status < VI_SUCCESS)
{
printf("Could not open a session to the VISA Resource Manager!\n");
exit (EXIT_FAILURE);
}
status = viOpen (defaultRM, "visa://137.138.179.180/PXI16::12::INSTR", VI_NULL, VI_NULL, &instr);
if (status < VI_SUCCESS)
{
printf("Can not open a VISA session to visa://137.138.179.180/PXI16::12::INSTR\n");
viClose (defaultRM);
exit (EXIT_SUCCESS);
}
/*Now we will install the event handler that will monitor interrupt events. The handler is named IntrHandler. uhandle is a handle
* allowing data to be passed to the handler from the application. */
status = viInstallHandler (instr, VI_EVENT_PXI_INTR, IntrHandler, VI_NULL);
// status = viInstallHandler (instr, VI_EVENT_EXCEPTION, IntrHandler, VI_NULL);
if (status < VI_SUCCESS)
{
printf("Could not install the interrupt handler.\n");
viClose (defaultRM);
exit (EXIT_SUCCESS);
}
/*
* Now we will enable signal processing events so the program can receive them into its event handler. It will only receive events for
* interrupts or signals. See the other interrupt example to see how things would differ if events were queued. */
status = viEnableEvent (instr, VI_EVENT_PXI_INTR, VI_HNDLR, VI_NULL);
// status = viEnableEvent (instr, VI_EVENT_EXCEPTION, VI_HNDLR, VI_NULL);
if (status < VI_SUCCESS)
{
printf("Could not enable the interrupt event.\n");
viClose (defaultRM);
exit (EXIT_SUCCESS);
}
/*
* Under Windows 3.x or the Macintosh, Yield() or PeekMessage() functions may need to be called to give up processor time so that VISA events
* will be invoked. Under WIN32 or UNIX, this is not necessary because VISA event handlers are spawned in a separate thread. */
printf("Press any key to stop waiting for events.\n");
fflush(stdin);
tempchar=getchar();
/* Now we will uninstall the handler we installed to handle interrupts Calling this function will implicitly call viDisableEvent().
* Note that unlike viWaitonEvent, the event is closed for us when we exit the handler. Compare this with the other interrupt example. */
status = viUninstallHandler (instr, VI_EVENT_VXI_SIGP, IntrHandler, VI_NULL);
/* Now we will close the session to the instrument using viClose. We will tell VISA what to close using the handle, "instr". */
viClose (instr);
viClose (defaultRM);
printf("\nHit Enter to continue.");
fflush(stdin);
getchar();
return 0;
}
When the program executes the line
status = viEnableEvent (instr, VI_EVENT_PXI_INTR, VI_HNDLR, VI_NULL);
an error appears:
Function viEnableEvent: (return value == -1073807302 [0xbfff003a]). Unable to start operation because setup is invalid (due to attributes being set to an inconsistent state).
If I run the program configuring the other event in the code (and also changing the properties in the handler)
// status = viInstallHandler (instr, VI_EVENT_EXCEPTION, IntrHandler, VI_NULL);
the program works fine...Has someone an idea why i have this error when I use the event VI_EVENT_PXI_INTR?
Also I have another question about interruptions with PXI. Thefinalgoal is to develop a program that calls dll´s made withLabWindows anddetectthepossibleinterruptions in the PXI. I have been looking for some examples but I haven´t seen anything similar...Has someone a practical examples of how to handle interruptions with LabVIEW?
Thanks,
Jaime
