This example sets up a periodic interval timer of 2 seconds, lets it run for a while, and finally stops it.

 #define INCL_DOSSEMAPHORES   /* Semaphore values */
 #define INCL_DOSDATETIME     /* Timer support    */
 #define INCL_DOSERRORS       /* DOS error values */
 #include <os2.h>
 #include <stdio.h>

 int main(VOID) {

 HEV     hevEvent1     = 0;                   /* Event semaphore handle    */
 HTIMER  htimerEvent1  = 0;                   /* Timer handle              */
 APIRET  rc            = NO_ERROR;            /* Return code               */
 ULONG   ulPostCount   = 0;                   /* Semaphore post count      */
 ULONG   i             = 0;                   /* A loop index              */

    rc = DosCreateEventSem(NULL,           /* Unnamed semaphore            */
                           &hevEvent1,     /* Handle of semaphore returned */
                           DC_SEM_SHARED,  /* Indicate a shared semaphore  */
                           FALSE);         /* Put in RESET state           */
    if (rc != NO_ERROR) {
        printf("DosCreateEventSem error: return code = %u\n", rc);
        return 1;
    }

    rc = DosStartTimer(2000L,              /* 2 second interval            */
                       (HSEM) hevEvent1,   /* Semaphore to post            */
                       &htimerEvent1);     /* Timer handler (returned)     */
    if (rc != NO_ERROR) {
        printf("DosStartTimer error: return code = %u\n", rc);
        return 1;
    }

    for (i = 1 ; i < 6 ; i++) {

      rc = DosWaitEventSem(hevEvent1,15000L); /* Wait 15 seconds for timer */
      if (rc != NO_ERROR) {
          printf("DosWaitEventSem error: return code = %u\n", rc);
          return 1;
      }

      rc = DosResetEventSem(hevEvent1,       /* Reset the semaphore         */
                            &ulPostCount);   /* And get count (should be 1) */
      if (rc != NO_ERROR) {
          printf("DosWaitEventSem error: return code = %u\n", rc);
          return 1;
      }

      printf("Iteration %u: ulPostCount = %u\n", i, ulPostCount);

    } /* for loop */
    rc = DosStopTimer(htimerEvent1);       /* Stop the timer             */
    if (rc != NO_ERROR) {
        printf("DosCloseEventSem error: return code = %u\n", rc);
        return 1;
    }

    rc = DosCloseEventSem(hevEvent1);      /* Get rid of semaphore       */
    if (rc != NO_ERROR) {
        printf("DosCloseEventSem error: return code = %u\n", rc);
        return 1;
    }

 return NO_ERROR;
}