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AR# 34567

11.4 ISE Simulator (ISim) - Bi-directional signals are not initialized during simulation restart


I have a design with bi-directional signals.It simulates successfully when I first run the simulation. However, when I restart the simulation, the simulation fails because the bi-directional signals are not assigned default values as defined in the HDL:

tbio <= TB_INOUT_Z;

where TB_INOUT_Z is defined as a constant via the following HDL

TYPE tb_inout IS
inout_sig : STD_LOGIC;
out_sig : STD_LOGIC;

CONSTANT TB_INOUT_Z : tb_inout :=
inout_sig => 'Z',
out_sig => 'Z'

How can I resolve this issue?


This is an issue in ISE Simulator 11. It has been resolved in ISE Design Suite 12.

To download and install the latest version of ISE Design Suite, visit the Download Center at http://www.xilinx.com/support/download/index.htm

Linked Answer Records

Associated Answer Records

Answer Number Answer Title Version Found Version Resolved
33381 ISE Design Suite 11 - ISE Simulator (ISim) Known Issues N/A N/A
AR# 34567
Date Created 03/03/2010
Last Updated 12/15/2012
Status Active
Type General Article
  • ISE Design Suite - 11.1
  • ISE Design Suite - 11.2
  • ISE Design Suite - 11.3
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  • ISE Design Suite - 11.4
  • ISE Design Suite - 11.5
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