comedi_dio_bitfield2(3) read/write multiple digital channels


#include <comedilib.h>

int comedi_dio_bitfield2(comedi_t * device, unsigned int subdevice, unsigned int write_mask, unsigned int * bits, unsigned int base_channel);


The function comedi_dio_bitfield2 allows multiple channels to be read or written together on a digital input, output, or configurable digital I/O device. The parameter write_mask and the value pointed to by bits are interpreted as bit fields, with the least significant bit representing channel base_channel. For each bit in write_mask that is set to 1, the corresponding bit in *bits is written to the digital output channel. After writing all the output channels, each channel is read, and the result placed in the approprate bits in *bits. The result of reading an output channel is the last value written to the output channel.

All the channels might not be read or written at the exact same time. For example, the driver may need to sequentially write to several registers in order to set all the digital channels specified by the write_mask and base_channel parameters.


If successful, 0 is returned, otherwise -1.


David Schleef <[email protected]>


Frank Mori Hess <[email protected]>


Herman Bruyninckx <[email protected]>


Bernd Porr <[email protected]>


Ian Abbott <[email protected]>


Éric Piel <[email protected]>



Copyright © 1998-2003 David Schleef
Copyright © 2001-2003, 2005, 2008 Frank Mori Hess
Copyright © 2002-2003 Herman Bruyninckx
Copyright © 2012 Bernd Porr
Copyright © 2012 Ian Abbott
Copyright © 2012 Éric Piel

This document is part of Comedilib. In the context of this document, the term "source code" as defined by the license is interpreted as the XML source.

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, version 2.1 of the License.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.