ni_660x_set_pfi_direction
ni_660x_set_pfi_direction(dev, i, COMEDI_INPUT);/* high-z */
ni_660x_set_pfi_direction(dev, chan, COMEDI_OUTPUT);
ni_660x_set_pfi_direction(dev, chan, COMEDI_INPUT);
ni_660x_set_pfi_direction(dev, dest, COMEDI_OUTPUT);
ni_660x_set_pfi_direction(dev, dest, COMEDI_INPUT);