AR# 9717


ModelSim (MXE, SE, PE) - UniSim components are not picked up for Verilog designs


General Description:

When my Verilog design is loaded in ModelSim, the UniSim libraries are not used, even though I have them mapped correctly. Why does this happen?


The library mapping information displays logical library names to physical locations. These mappings are not used as a search list when simulation is loaded in ModelSim.

For Verilog, a library search list needs to be specified. This can be done either through a `uselib directive in the source code, or while the simulation is loading in ModelSim. The VSim command line would look like:

vsim -L <library_name> work.toplevel work.glbl

where <library_name> will be the UniSim/SimPrim library to be used.

The syntax for the 'uselib command is as follows:

`uselib lib=<library_mapping_name>

where the <library_mapping_name> is the alias assigned to the library in ModelSim. To see what these libraries have been mapped to, go to Design -> Browse Libraries from the pull-down menu in ModelSim.

If this switch is not used, errors similar to the following occur:

"# ERROR: C:/pathtofile/myfilename.v(96): Instantiation of 'SRL16' failed (design unit not found).

# Region: /myfilename

# Searched libraries:

# work"

For more information on the usage of the "glbl.v" file, please see (Xilinx Answer 6537).

AR# 9717
Date 12/15/2012
Status Active
Type General Article
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