Preserve register for signal tap debug - Preserve register for signal tap debug Unable to preserve register with no fan out using following: set_instance_assignment -name PRESERVE_REGISTER ON -to reg1 set_instance_assignment -name PRESERVE_FANOUT_FREE_NODE ON -to reg1 similar result using assignment editor - can't find reg1 available at pre-synthesis Replies: Re: Preserve register for signal tap debug Mark, You may refer to below link for preserving register nodes using noprune in your hdl https://www.intel.com/content/www/us/en/programmable/quartushelp/17.0/hdl/vlog/vlog_file_dir_noprune.htm Replies: Re: Preserve register for signal tap debug solution found: reg reg1 /*synthesis noprune */; BR, Mark.