/* evnthdlr.c

   This example program illustrates installing an event handler to

   be called when a trigger interrupt occurs. Note that you must

   change the address. */

#include <visa.h>

#include <stdio.h>

/* trigger event handler */

ViStatus _VI_FUNCH myHdlr(ViSession vi, ViEventType eventType,

                          ViEvent ctx, ViAddr userHdlr){

   ViInt16 trigId;

   /* make sure it is a trigger event */

   if(eventType!=VI_EVENT_TRIG){

      /* Stray event, so ignore */

      return VI_SUCCESS;

   }

   /* print the event information */

   printf("Trigger Event Occurred!\n");

   printf("...Original Device Session = %ld\n", vi);

   /* get the trigger that fired */

   viGetAttribute(ctx, VI_ATTR_RECV_TRIG_ID, &trigId);

   printf("Trigger that fired: ");

   switch(trigId){

      case VI_TRIG_TTL0:

         printf("TTL0");

         break;

      default:

         printf("<other 0x%x>", trigId);

         break;

   }

   printf("\n");

   return VI_SUCCESS;

}

void main(){

   ViSession defaultRM,vi;

   /* open session to VXI device */

   viOpenDefaultRM(&defaultRM);

   viOpen(defaultRM, "VXI0::24::INSTR", VI_NULL, VI_NULL, &vi);

   /* select trigger line TTL0 */

   viSetAttribute(vi, VI_ATTR_TRIG_ID, VI_TRIG_TTL0);

   /* install the handler and enable it */

   viInstallHandler(vi, VI_EVENT_TRIG, myHdlr, (ViAddr)10);

   viEnableEvent(vi, VI_EVENT_TRIG, VI_HNDLR, VI_NULL);

   /* fire trigger line, twice */

   viAssertTrigger(vi, VI_TRIG_PROT_SYNC);

   viAssertTrigger(vi, VI_TRIG_PROT_SYNC);

   /* unenable and uninstall the handler */

   viDisableEvent(vi, VI_EVENT_TRIG, VI_HNDLR);

   viUninstallHandler(vi, VI_EVENT_TRIG, myHdlr, (ViAddr)10);

   /* close the sessions */

   viClose(vi);

   viClose(defaultRM);

}