comedi_data_read_delayed man page
comedi_data_read_delayed — read single sample from channel after delaying for specified settling time
int comedi_data_read_delayed (comedi_t * device, unsigned int subdevice, unsigned int channel, unsigned int range, unsigned int aref, lsampl_t * data, unsigned int nanosec);
Similar to comedi_data_read() except it will wait for the specified number of nanoseconds between setting the input channel and taking a sample. For analog inputs, most boards have a single analog to digital converter which is multiplexed to be able to read multiple channels. If the input is not allowed to settle after the multiplexer switches channels, the reading will be inaccurate. This function is useful for allowing a multiplexed analog input to settle when switching channels.
Although the settling time is specified in nanoseconds, the actual settling time will be rounded up to the nearest microsecond.