Psychtoolbox>Datapixx.{mex*} subfunction

Enable an internal loopback from the digital outputs to the digital inputs. This
causes values programmed into the digital output bits to appear on the
corresponding digital input bits. This convenient feature can be useful when
developing complex triggers or other digital output waveforms. The generated
DOUT waveforms can be examined using the DIN logging system.
See DatapixxDin*Demo files for examples.

###See also: DisableDoutDinLoopback, GetDinStatus