... comedi_dio_bitfield -- read/write multiple digital channels . ... int comedi_dio_bitfield (comedi_t * device, unsigned int subdevice, unsigned int write_mask, unsigned int * bits); . ... For each bit in write_mask that is set to 1, the cooresponding 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 undefined. ...