We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 35869

MIG - v3.4 - Spartan-6 - When simulating the example design with ModelSim PE I get an "Iteration limit" error.


When simulating the MIG v3.4 example design with the ISE software 12.1 simulation models using ModelSim PE, the following error message is received:

# ** Error: (vsim-3601) Iteration limit reached at time 20313750 ps.
# Could not find any active process to start the loop analysis.
# Executing ONERROR command at macro ./sim.do line 140


This is due to a known issue in the simulation model which only affects ModelSim PE.  

If you are using ModelSim SE, you will not see this problem.

To work around the issue, you must download patched MCB.vp files here: 


To recompile the MCB secureIP model do the following:

1) Use any unzip utility to extract this file to a temporary location.

2) Once the files have been extracted run the below commands in the ModelSim Console after changing directory to the location of he file extraction.

Vlog -work secureip -f  mcb_cell.list.f

This is resolved in ISE version 12.2. 

If you are using ISE software 12.2 or later, you do not need this patch. 

If you are using ISE software 11.5 or earlier, you do not need this patch. 

Note: You will have to recompile your simulation models after installing the ISE software 12.2 update.

AR# 35869
Date Created 05/28/2010
Last Updated 09/03/2014
Status Active
Type General Article
  • Spartan-6 LX
  • Spartan-6 LXT
  • MIG