The parameter comedi needs to be set to a valid Comedi device handle, i.e., needs to be set to the record member dh of a ComediConfig record instance.
Wraps the Comedi function comedi_data_read(..). See the Comedi documentation for the meanings of the parameters subDevice, channel, range, aref.
Only supported for Linux, since Comedi is only available for linux (http://www.comedi.org/). Requires that Comedilib is installed and that the simulation process has sufficient privileges to access the intended device (usually that means "root" privileges).