1COMEDI_DATA_READ(3)                                        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, unsigned int aref, lsampl_t *
13       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 places the data value in the location pointed to by data.
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26       WARNING:  comedi_data_read()  does  not  do any pausing to allow multi‐
27       plexed analog inputs to settle before performing an analog  to  digital
28       conversion.   If  you are switching between different channels and need
29       to 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       On sucess, comedi_data_read() returns 1 (the number of  samples  read).
34       If there is an error, -1 is returned.
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36       Data  values  returned by this function are unsigned integers less than
37       or equal to the maximum sample value  of  the  channel,  which  can  be
38       determined using the function comedi_get_maxdata().  Conversion of data
39       values  to  physical  units  can   be   performed   by   the   function
40       comedi_to_phys().
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42                                28 October 2007            COMEDI_DATA_READ(3)