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AR# 15985

5.1i ISE - Project Navigator incorrectly passes a value for "Global Disable of X-generation for Simulation" (-xon)


Keywords: NGD2VHDL, xon, simulation, Global, disable, x-generation, undefined, propagation, timing, violation

Urgency: Standard

General Description:
The "Global Disable of X-generation for Simulation" property is available for VHDL in the "Generate Post Place-and-Route Simulation Model" properties. When this property is de-selected, the NGD2VHDL command should be "-xon true", and when it is selected, the NGD2VHDL command should be "-xon false".

However, in Project Navigator 5.1i, the opposite currently occurs. By default, this disables X propagation, which can cause critical violations to be missed in simulation.


This problem is fixed in the latest 5.1i Service Pack, available at:
The first service pack containing the fix is 5.1i Service Pack 3.

With 5.1i Service Pack 3, Project Navigator will continue to leave the option de-selected by default, but will pass "-xon true" when not selected and "-xon false" when it is selected.

Until Service Pack 3 is installed, you should be aware of this issue and check the View Command Line Log File under "Design Entry Utilities" to verify that the correct value for NGD2VHDL -xon is being passed.
AR# 15985
Date Created 10/23/2002
Last Updated 02/07/2006
Status Archive
Type General Article