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       comedi_data_read - read single sample from channel


       #include <comedilib.h>

       int  comedi_data_read  (comedi_t  *  device,  unsigned  int  subdevice,
       unsigned int channel, unsigned int range, unsigned int aref, lsampl_t *


       Reads  a  single  sample  on the channel specified by the Comedi device
       device, the subdevice subdevice, and the channel channel.  For the  A/D
       conversion  (if  appropriate),  the  device  is configured to use range
       specification range and (if appropriate) analog  reference  type  aref.
       Analog  reference  types  that  are  not  supported  by  the device are
       silently ignored.

       The function comedi_data_read() reads one data value from the specified
       channel and places the data value in the location pointed to by data.

       WARNING:   comedi_data_read()   does   not  do  any  pausing  to  allow
       multiplexed analog inputs to settle  before  performing  an  analog  to
       digital  conversion.   If  you are switching between different channels
       and need to allow your analog input to settle for an accurate  reading,
       use  comedi_data_read_delayed(), or set the input channel at an earlier
       time with comedi_data_read_hint().

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

       Data  values  returned by this function are unsigned integers less than
       or equal to the maximum sample value  of  the  channel,  which  can  be
       determined using the function comedi_get_maxdata().  Conversion of data
       values  to  physical  units  can   be   performed   by   the   function

                                28 October 2007