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alter.c

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/*
  alter.c

  Sample external process that dynamically alters the input position
  of the EMC's 'axis', using a sine wave of frequency 'freq' (Hz), with
  amplitude 'range'. Syntax is:

  alter -axis <axis> -freq <freq> -range <range> -ini <inifile>

  Any or all args can be omitted. Default is 0, 1.0, 1.0, and emc.ini,
  respectively.

  The alter interface is intended to support dynamic compensations of small
  amounts based on a sensor-based machine model, for example from temperature.
*/

#include <stdio.h>              /* fprintf(), stderr */
#include <string.h>             /* strncmp() */
#include <stdlib.h>             /* exit() */
#include <float.h>              /* DBL_MIN */
#include <signal.h>             /* SIGINT, signal() */
#include <math.h>               /* sin() */
#include <unistd.h>             /* usleep() */
#include "emcmotglb.h"          /* EMC_INIFILE */
#include "usrmotintf.h"         /* usrmotIniLoad(), usrmotInit(),
                                   usrmotAlter(), usrmotQueryAlter() */

#define TWO_PI 6.28318530717958647692
#define SLEEP_USECS 10000

static int done = 0;
static void quit(int sig)
{
  done = 1;
}

int main(int argc, char *argv[])
{
  int t;
  int axis = 0;
  double range = 1.0;
  double freq = 1.0;
  double freqinv = 1.0;
  double alter;
  double x;

  /* look for EMC_INIFILE, or leave as default if not found */
  for (t = 1; t < argc; t++) {
    if (! strcmp(argv[t], "-ini")) {
      /* make sure -ini isn't last, since we'll look at next arg */
      if (t == argc - 1) {
        fprintf(stderr, "can't read -ini parameter; using default %s\n", EMCMOT_INIFILE);
      }
      else {
        /* got it */
        strncpy(EMCMOT_INIFILE, argv[t + 1], EMCMOT_INIFILE_LEN - 1);
        EMCMOT_INIFILE[EMCMOT_INIFILE_LEN - 1] = 0;
        t++;                    /* step over arg */
      }
      continue;
    }
    if (! strcmp(argv[t], "-axis")) {
      /* make sure -axis isn't last, since we'll look at next arg */
      if (t == argc - 1) {
        fprintf(stderr, "can't read -axis parameter; using default %d\n", axis);
      }
      else {
        if (1 != sscanf(argv[t + 1], "%d", &axis)) {
          fprintf(stderr, "bad value for axis: %s\n", argv[t + 1]);
          exit(1);
        }
        /* got it */
        t++;                    /* step over arg */
      }
      continue;
    }
    if (! strcmp(argv[t], "-range")) {
      /* make sure -range isn't last, since we'll look at next arg */
      if (t == argc - 1) {
        fprintf(stderr, "can't read -range parameter; using default %f\n", range);
      }
      else {
        if (1 != sscanf(argv[t + 1], "%lf", &range)) {
          fprintf(stderr, "bad value for range: %s\n", argv[t + 1]);
          exit(1);
        }
        /* got it */
        t++;                    /* step over arg */
      }
      continue;
    }
    if (! strcmp(argv[t], "-freq")) {
      /* make sure -freq isn't last, since we'll look at next arg */
      if (t == argc - 1) {
        fprintf(stderr, "can't read -freq parameter; using default %f\n", freq);
      }
      else {
        if (1 != sscanf(argv[t + 1], "%lf", &freq) ||
            freq < DBL_MIN) {
          fprintf(stderr, "bad value for freq: %s\n", argv[t + 1]);
          exit(1);
        }
        /* got it */
        freqinv = 1.0 / freq;   /* already checked freq against DBL_MIN */
        t++;                    /* step over arg */
      }
      continue;
    }
  }

  if (0 != usrmotIniLoad(EMCMOT_INIFILE)) {
    fprintf(stderr, "can't initialize from %s\n", EMCMOT_INIFILE);
    exit(1);
  }

  if (0 != usrmotInit()) {
    fprintf(stderr, "can't connect to motion controller\n");
    exit(1);
  }

  done = 0;
  signal(SIGINT, quit);
  x = 0;

  while (! done) {
    alter = range * sin(TWO_PI * freq * x);
    usrmotAlter(axis, alter);
    x += ((double) SLEEP_USECS) / 1000000.0;
    if (x > freqinv) {
      x = 0.0;
    }
    usleep(SLEEP_USECS);
  }

  usrmotExit();

  exit(0);
}

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