1COMEDI_DATA_READ(3)            Comedi reference            COMEDI_DATA_READ(3)
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NAME

6       comedi_data_read - read single sample from channel
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SYNOPSIS

9       #include <comedilib.h>
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11       int comedi_data_read(comedi_t * device, unsigned int subdevice,
12                            unsigned int channel, unsigned int range,
13                            unsigned int aref, lsampl_t * data);
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DESCRIPTION

16       Reads a single sample on the channel specified by the Comedi device
17       device, the subdevice subdevice, and the channel channel. For the A/D
18       conversion (if appropriate), the device is configured to use range
19       specification range and (if appropriate) analog reference type aref.
20       Analog reference types that are not supported by the device are
21       silently ignored.
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23       The function comedi_data_read reads one data value from the specified
24       channel and stores the value in *data.
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26       WARNING: comedi_data_read does not do any pausing to allow multiplexed
27       analog inputs to settle before starting an analog to digital
28       conversion. If you are switching between different channels and need to
29       allow your analog input to settle for an accurate reading, use
30       comedi_data_read_delayed, or set the input channel at an earlier time
31       with comedi_data_read_hint.
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33       Data values returned by this function are unsigned integers less than
34       or equal to the maximum sample value of the channel, which can be
35       determined using the function comedi_get_maxdata. Conversion of data
36       values to physical units can be performed by the functions
37       comedi_to_phys (linear conversion) or comedi_to_physical (non-linear
38       polynomial conversion).
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RETURN VALUE

41       On success, comedi_data_read returns 1 (the number of samples read). If
42       there is an error, -1 is returned.
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AUTHORS

45       David Schleef <ds@schleef.org>
46           Author.
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48       Frank Mori Hess <fmhess@users.sourceforge.net>
49           Author.
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51       Herman Bruyninckx <Herman.Bruyninckx@mech.kuleuven.ac.be>
52           Author.
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54       Bernd Porr <tech@linux-usb-daq.co.uk>
55           Author.
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57       Ian Abbott <abbotti@mev.co.uk>
58           Author.
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60       Éric Piel <piel@delmic.com>
61           Author.
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64       Copyright © 1998-2003 David Schleef
65       Copyright © 2001-2003, 2005, 2008 Frank Mori Hess
66       Copyright © 2002-2003 Herman Bruyninckx
67       Copyright © 2012 Bernd Porr
68       Copyright © 2012 Ian Abbott
69       Copyright © 2012, 2015 Éric Piel
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71       This document is part of Comedilib. In the context of this document,
72       the term "source code" as defined by the license is interpreted as the
73       XML source.
74
75       This library is free software; you can redistribute it and/or modify it
76       under the terms of the GNU Lesser General Public License as published
77       by the Free Software Foundation, version 2.1 of the License.
78
79       This library is distributed in the hope that it will be useful, but
80       WITHOUT ANY WARRANTY; without even the implied warranty of
81       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
82       General Public License for more details.
83
84       You should have received a copy of the GNU Lesser General Public
85       License along with this library; if not, write to the Free Software
86       Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
87       USA.
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92Comedi                            05/11/2017               COMEDI_DATA_READ(3)
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