comedi_data_read with pci-das6402/16

Readme.txt

I've made a small modification to the tut2.c demo to have it call
comedi_data_read() three times for each range available on a pci-das6402/16 on
channel 0 and then again on channel 1.  For the test, I've configured for about
0.4V to be applied on differential channel 0, and I've jumpered channel 1 so
that it has 0V on it.  

I'm seeing three problems: 

1) The first reading in each range looks erroneous.  Is this an instance where
comedi_data_read_hint() should be called with a short settling time before
calling comedi_data_read()?  

2) The conversion to a physical value for ranges 4, 5, and 6 seems to be off by
a factor of two.  

3) The readings in range 7 have raw values around 2591, when I would have
expected to see something like 42000.  

This could be related to the trouble I'm having with comedi_calibrate on this
board.  (See my earlier email.)  

board_info.txt

overall info:
  version code: 0x00074c
  driver name: cb_pcidas64
  board name: pci-das6402/16
  number of subdevices: 10
subdevice 0:
  type: 1 (analog input)
  flags: 0x01519000
  number of channels: 64
  max data value: 65535
  ranges:
    all chans: [-10,10] [-5,5] [-2.5,2.5] [-1.25,1.25] [0,10] [0,5] [0,2.5] [0,1.25]
  command:
    start: now|ext
    scan_begin: follow|timer
    convert: timer|ext
    scan_end: count
    stop: none|count|ext
  command fast 1chan:
    start: now 0
    scan_begin: follow 0
    convert: timer 5000
    scan_end: count 1
    stop: count 2
subdevice 1:
  type: 2 (analog output)
  flags: 0x00135000
  number of channels: 2
  max data value: 65535
  ranges:
    all chans: [-5,5] [-10,10] [0,5] [0,10]
  command:
    start: ext|int
    scan_begin: timer|ext
    convert: now
    scan_end: count
    stop: none
  command fast 1chan:
    start: int 0
    scan_begin: timer 10000
    convert: now 0
    scan_end: count 1
    stop: none 0
subdevice 2:
  type: 3 (digital input)
  flags: 0x00010000
  number of channels: 4
  max data value: 1
  ranges:
    all chans: [0,5]
  command:
    not supported
subdevice 3:
  type: 4 (digital output)
  flags: 0x00030000
  number of channels: 4
  max data value: 1
  ranges:
    all chans: [0,5]
  command:
    not supported
subdevice 4:
  type: 5 (digital I/O)
  flags: 0x00030000
  number of channels: 24
  max data value: 1
  ranges:
    all chans: [0,5]
  command:
    not supported
subdevice 5:
  type: 0 (unused)
subdevice 6:
  type: 9 (calibration)
  flags: 0x00070000
  number of channels: 8
  max data value: 255
  ranges:
    all chans: [0,1]
  command:
    not supported
subdevice 7:
  type: 9 (calibration)
  flags: 0x00070000
  number of channels: 2
  max data value: 255
  ranges:
    all chans: [0,1]
  command:
    not supported
subdevice 8:
  type: 8 (memory)
  flags: 0x00050000
  number of channels: 128
  max data value: 65535
  ranges:
    all chans: [0,1]
  command:
    not supported
subdevice 9:
  type: 0 (unused)

tut2-mod-out-2.txt

--- setting range to 0 ---
[0,65535] -> [-10,10] --- -0.287938 V (31824 in raw units)
[0,65535] -> [-10,10] --- 0.202487 V (33431 in raw units)
[0,65535] -> [-10,10] --- 0.202182 V (33430 in raw units)
[0,65535] -> [-10,10] --- 0.200656 V (33425 in raw units)
--- setting range to 1 ---
[0,65535] -> [-5,5] --- 0.19585 V (34051 in raw units)
[0,65535] -> [-5,5] --- 0.201038 V (34085 in raw units)
[0,65535] -> [-5,5] --- 0.202411 V (34094 in raw units)
[0,65535] -> [-5,5] --- 0.201801 V (34090 in raw units)
--- setting range to 2 ---
[0,65535] -> [-2.5,2.5] --- 0.1981 V (35364 in raw units)
[0,65535] -> [-2.5,2.5] --- 0.201228 V (35405 in raw units)
[0,65535] -> [-2.5,2.5] --- 0.200465 V (35395 in raw units)
[0,65535] -> [-2.5,2.5] --- 0.201839 V (35413 in raw units)
--- setting range to 3 ---
[0,65535] -> [-1.25,1.25] --- 0.197776 V (37952 in raw units)
[0,65535] -> [-1.25,1.25] --- 0.201019 V (38037 in raw units)
[0,65535] -> [-1.25,1.25] --- 0.201095 V (38039 in raw units)
[0,65535] -> [-1.25,1.25] --- 0.201438 V (38048 in raw units)
--- setting range to 4 ---
[0,65535] -> [0,10] --- 0.508278 V (3331 in raw units)
[0,65535] -> [0,10] --- 0.202792 V (1329 in raw units)
[0,65535] -> [0,10] --- 0.199893 V (1310 in raw units)
[0,65535] -> [0,10] --- 0.200961 V (1317 in raw units)
--- setting range to 5 ---
[0,65535] -> [0,5] --- 0.191119 V (2505 in raw units)
[0,65535] -> [0,5] --- 0.200504 V (2628 in raw units)
[0,65535] -> [0,5] --- 0.200732 V (2631 in raw units)
[0,65535] -> [0,5] --- 0.200732 V (2631 in raw units)
--- setting range to 6 ---
[0,65535] -> [0,2.5] --- 0.191424 V (5018 in raw units)
[0,65535] -> [0,2.5] --- 0.201152 V (5273 in raw units)
[0,65535] -> [0,2.5] --- 0.201076 V (5271 in raw units)
[0,65535] -> [0,2.5] --- 0.200427 V (5254 in raw units)
--- setting range to 7 ---
[0,65535] -> [0,1.25] --- 0.193465 V (10143 in raw units)
[0,65535] -> [0,1.25] --- 0.201305 V (10554 in raw units)
[0,65535] -> [0,1.25] --- 0.201038 V (10540 in raw units)
[0,65535] -> [0,1.25] --- 0.201247 V (10551 in raw units)
-+-+- setting channel to 1 -+-+-
--- setting range to 0 ---
[0,65535] -> [-10,10] --- -0.110628 V (32405 in raw units)
[0,65535] -> [-10,10] --- 0.00015259 V (32768 in raw units)
[0,65535] -> [-10,10] --- 0.00015259 V (32768 in raw units)
[0,65535] -> [-10,10] --- 0.00015259 V (32768 in raw units)
--- setting range to 1 ---
[0,65535] -> [-5,5] --- -0.00236515 V (32752 in raw units)
[0,65535] -> [-5,5] --- -7.62951e-05 V (32767 in raw units)
[0,65535] -> [-5,5] --- 7.62951e-05 V (32768 in raw units)
[0,65535] -> [-5,5] --- 0.000381476 V (32770 in raw units)
--- setting range to 2 ---
[0,65535] -> [-2.5,2.5] --- -0.000343328 V (32763 in raw units)
[0,65535] -> [-2.5,2.5] --- -0.000343328 V (32763 in raw units)
[0,65535] -> [-2.5,2.5] --- -0.000114443 V (32766 in raw units)
[0,65535] -> [-2.5,2.5] --- 0.000190738 V (32770 in raw units)
--- setting range to 3 ---
[0,65535] -> [-1.25,1.25] --- 0.00246052 V (32832 in raw units)
[0,65535] -> [-1.25,1.25] --- -9.53689e-05 V (32765 in raw units)
[0,65535] -> [-1.25,1.25] --- 1.90738e-05 V (32768 in raw units)
[0,65535] -> [-1.25,1.25] --- 1.90738e-05 V (32768 in raw units)
--- setting range to 4 ---
[0,65535] -> [0,10] --- 0.215152 V (1410 in raw units)
[0,65535] -> [0,10] --- NaN [0,10] 0 in raw units
[0,65535] -> [0,10] --- NaN [0,10] 0 in raw units
[0,65535] -> [0,10] --- NaN [0,10] 0 in raw units
--- setting range to 5 ---
[0,65535] -> [0,5] --- NaN [0,5] 0 in raw units
[0,65535] -> [0,5] --- NaN [0,5] 0 in raw units
[0,65535] -> [0,5] --- NaN [0,5] 0 in raw units
[0,65535] -> [0,5] --- NaN [0,5] 0 in raw units
--- setting range to 6 ---
[0,65535] -> [0,2.5] --- 3.81476e-05 V (1 in raw units)
[0,65535] -> [0,2.5] --- NaN [0,2.5] 0 in raw units
[0,65535] -> [0,2.5] --- NaN [0,2.5] 0 in raw units
[0,65535] -> [0,2.5] --- NaN [0,2.5] 0 in raw units
--- setting range to 7 ---
[0,65535] -> [0,1.25] --- 0.00322347 V (169 in raw units)
[0,65535] -> [0,1.25] --- NaN [0,1.25] 0 in raw units
[0,65535] -> [0,1.25] --- NaN [0,1.25] 0 in raw units
[0,65535] -> [0,1.25] --- NaN [0,1.25] 0 in raw units

tut2-mod-out.txt

--- setting range to 0 ---
[0,65535] -> [-10,10] --- -0.0224308 V (32694 in raw units)
[0,65535] -> [-10,10] --- 0.411231 V (34115 in raw units)
[0,65535] -> [-10,10] --- 0.408179 V (34105 in raw units)
--- setting range to 1 ---
[0,65535] -> [-5,5] --- 0.400015 V (35389 in raw units)
[0,65535] -> [-5,5] --- 0.406577 V (35432 in raw units)
[0,65535] -> [-5,5] --- 0.407034 V (35435 in raw units)
--- setting range to 2 ---
[0,65535] -> [-2.5,2.5] --- 0.398528 V (37991 in raw units)
[0,65535] -> [-2.5,2.5] --- 0.405241 V (38079 in raw units)
[0,65535] -> [-2.5,2.5] --- 0.405165 V (38078 in raw units)
--- setting range to 3 ---
[0,65535] -> [-1.25,1.25] --- 0.395304 V (43130 in raw units)
[0,65535] -> [-1.25,1.25] --- 0.404231 V (43364 in raw units)
[0,65535] -> [-1.25,1.25] --- 0.404192 V (43363 in raw units)
--- setting range to 4 ---
[0,65535] -> [0,10] --- 1.09209 V (7157 in raw units)
[0,65535] -> [0,10] --- 0.799878 V (5242 in raw units)
[0,65535] -> [0,10] --- 0.800793 V (5248 in raw units)
--- setting range to 5 ---
[0,65535] -> [0,5] --- 0.767681 V (10062 in raw units)
[0,65535] -> [0,5] --- 0.802701 V (10521 in raw units)
[0,65535] -> [0,5] --- 0.802243 V (10515 in raw units)
--- setting range to 6 ---
[0,65535] -> [0,2.5] --- 0.768788 V (20153 in raw units)
[0,65535] -> [0,2.5] --- 0.804952 V (21101 in raw units)
[0,65535] -> [0,2.5] --- 0.804532 V (21090 in raw units)
--- setting range to 7 ---
[0,65535] -> [0,1.25] --- 0.0795949 V (4173 in raw units)
[0,65535] -> [0,1.25] --- 0.0494965 V (2595 in raw units)
[0,65535] -> [0,1.25] --- 0.0494202 V (2591 in raw units)
-+-+- setting channel to 1 -+-+-
--- setting range to 0 ---
[0,65535] -> [-10,10] --- -0.273899 V (31870 in raw units)
[0,65535] -> [-10,10] --- 0.00717174 V (32791 in raw units)
[0,65535] -> [-10,10] --- 0.0077821 V (32793 in raw units)
--- setting range to 1 ---
[0,65535] -> [-5,5] --- 0.00190738 V (32780 in raw units)
[0,65535] -> [-5,5] --- 0.00404364 V (32794 in raw units)
[0,65535] -> [-5,5] --- 0.00419623 V (32795 in raw units)
--- setting range to 2 ---
[0,65535] -> [-2.5,2.5] --- 0.00141146 V (32786 in raw units)
[0,65535] -> [-2.5,2.5] --- 0.00209812 V (32795 in raw units)
[0,65535] -> [-2.5,2.5] --- 0.00179294 V (32791 in raw units)
--- setting range to 3 ---
[0,65535] -> [-1.25,1.25] --- 0.00288014 V (32843 in raw units)
[0,65535] -> [-1.25,1.25] --- 0.00085832 V (32790 in raw units)
[0,65535] -> [-1.25,1.25] --- 0.000896468 V (32791 in raw units)
--- setting range to 4 ---
[0,65535] -> [0,10] --- 0.21149 V (1386 in raw units)
[0,65535] -> [0,10] --- Out of range [0,10]
[0,65535] -> [0,10] --- Out of range [0,10]
--- setting range to 5 ---
[0,65535] -> [0,5] --- Out of range [0,5]
[0,65535] -> [0,5] --- Out of range [0,5]
[0,65535] -> [0,5] --- Out of range [0,5]
--- setting range to 6 ---
[0,65535] -> [0,2.5] --- 0.00431067 V (113 in raw units)
[0,65535] -> [0,2.5] --- Out of range [0,2.5]
[0,65535] -> [0,2.5] --- Out of range [0,2.5]
--- setting range to 7 ---
[0,65535] -> [0,1.25] --- Out of range [0,1.25]
[0,65535] -> [0,1.25] --- Out of range [0,1.25]
[0,65535] -> [0,1.25] --- Out of range [0,1.25]

tut2-mod.c

/*
 * Tutorial example #2
 * Part of Comedilib
 *
 * Copyright (c) 1999,2000 David A. Schleef <[email protected]>
 * Copyright (c) 2008 Frank Mori Hess <[email protected]>
 *
 * This file may be freely modified, distributed, and combined with
 * other software, as long as proper attribution is given in the
 * source code.
 */

#include <stdio.h>		/* for printf() */
#include <stdlib.h>
#include <comedilib.h>
#include <ctype.h>
#include <math.h>

int subdev = 0;			/* change this to your input subdevice */
int chan = 0;			/* change this to your channel */
int range = 3;			/* more on this later */
int aref = AREF_DIFF;		/* more on this later */
const char filename[] = "/dev/comedi0";

int do_read(comedi_t *device, int subdev, int chan, int range, int aref)
{
	lsampl_t data;
	double physical_value;
	comedi_range * range_info;
	lsampl_t maxdata;
	int retval = comedi_data_read(device, subdev, chan, range, aref, &data);
	if(retval < 0)
	{
		comedi_perror(filename);
		exit(-1);
	}

	comedi_set_global_oor_behavior(COMEDI_OOR_NAN);
	range_info = comedi_get_range(device, subdev, chan, range);
	maxdata = comedi_get_maxdata(device, subdev, chan);
	printf("[0,%d] -> [%g,%g] --- ", maxdata,
	       range_info->min, range_info->max);
	physical_value = comedi_to_phys(data, range_info, maxdata);
	if(isnan(physical_value)) {
		printf("Out of range [%g,%g]\n",
		       range_info->min, range_info->max);
	} else {
		printf("%g", physical_value);
		switch(range_info->unit) {
		case UNIT_volt: printf(" V"); break;
		case UNIT_mA: printf(" mA"); break;
		case UNIT_none: break;
		default: printf(" (unknown unit %d)",
				range_info->unit);
		}
		printf(" (%lu in raw units)\n", (unsigned long)data);
	}
	return 0;
}

int main(int argc, char *argv[])
{
	comedi_t *device;
	int retval;

	device = comedi_open(filename);
	if(device == NULL)
	{
		comedi_perror(filename);
		return -1;
	}

	for(range = 0; range < 8; range++)
	{
		printf("--- setting range to %d ---\n", range);
		retval = do_read(device, subdev, chan, range, aref);
		retval = do_read(device, subdev, chan, range, aref);
		retval = do_read(device, subdev, chan, range, aref);
	}
	chan = 1;
	printf("-+-+- setting channel to %d -+-+-\n", chan);
	for(range = 0; range < 8; range++)
	{
		printf("--- setting range to %d ---\n", range);
		retval = do_read(device, subdev, chan, range, aref);
		retval = do_read(device, subdev, chan, range, aref);
		retval = do_read(device, subdev, chan, range, aref);
	}
	return 0;
}