Why do I see "X"s on my Reed-Solomon II encoder outputs? - Why do I see "X"s on my Reed-Solomon II encoder outputs? Description Due to a problem with the Quartus® Prime version 15.1 software, you will see this behavior if you instantiate more than one Reed-Solomon II (RS-II) IP core in your design. Resolution The problem occurs because the msim_setup.tcl file (or the equivalent for your simulator) compiles both instances into the same library. To work around this problem, edit the tcl script to add a new library, and move one of the instantiations to that library. For example you may see the following lines: ensure_lib ./libraries/_highspeed_rs_enc_151/ vmap altera_highspeed_rs_enc_151 ./libraries/altera_highspeed_rs_enc_151/ ... eval vlog -sv "/hs_rs_248_216_enc/altera_highspeed_rs_enc_151/sim/altera_highspeed_rs_enc_lagr_pkg.sv" -work altera_highspeed_rs_enc_151 eval vlog -sv "/hs_rs_248_232_enc/altera_highspeed_rs_enc_151/sim/altera_highspeed_rs_enc_lagr_pkg.sv" -work altera_highspeed_rs_enc_151 ... eval vsim -novopt -t ps -L work -L work_lib -L altera_common_sv_packages ... -L altera_highspeed_rs_enc_151 You would then modify as follows: ensure_lib ./libraries/_highspeed_rs_enc_151/ vmap altera_highspeed_rs_enc_151 ./libraries/altera_highspeed_rs_enc_151/ ensure_lib ./libraries/_highspeed_rs_enc_151_2/ vmap altera_highspeed_rs_enc_151_2 ./libraries/altera_highspeed_rs_enc_151_2/ ... eval vlog -sv "/hs_rs_248_216_enc/altera_highspeed_rs_enc_151/sim/altera_highspeed_rs_enc_lagr_pkg.sv" -work altera_highspeed_rs_enc_151 eval vlog -sv "/hs_rs_248_232_enc/altera_highspeed_rs_enc_151/sim/altera_highspeed_rs_enc_lagr_pkg.sv" -work altera_highspeed_rs_enc_151_2 ... eval vsim -novopt -t ps -L work -L work_lib -L altera_common_sv_packages ... -L altera_highspeed_rs_enc_151 -L altera_highspeed_rs_enc_151_2 This problem is scheduled to be fixed in a future Quartus Prime release. Custom Fields values: ['novalue'] Troubleshooting novalue False ['novalue'] ['FPGA Dev Tools Quartus® Prime Software Pro'] novalue 15.1 ['Arria® II GX FPGA', 'Arria® II GZ FPGA', 'Arria® V GT FPGA', 'Arria® V GX FPGA', 'Arria® V GZ FPGA', 'Arria® V ST FPGA', 'Arria® V SX FPGA', 'Cyclone® IV E FPGA', 'Cyclone® IV GX FPGA', 'Cyclone® V E FPGA', 'Cyclone® V GT FPGA', 'Cyclone® V GX FPGA', 'Cyclone® V SE FPGA', 'Cyclone® V ST FPGA', 'Cyclone® V SX FPGA', 'Arria® 10 GT FPGA', 'Arria® 10 GX FPGA', 'Arria® 10 SX FPGA', 'MAX® 10 10 FPGAs', 'Stratix® IV E FPGA', 'Stratix® IV GT FPGA', 'Stratix® IV GX FPGA', 'Stratix® V E FPGA', 'Stratix® V GS FPGA', 'Stratix® V GT FPGA', 'Stratix® V GX FPGA'] ['novalue'] ['novalue'] ['novalue']