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AR# 31566

10.1 Constraints System - PERIOD constraints are not being propagated through DCM


Keywords: pushed, replicated, derived, incorrect, missing

The PERIOD constraint that is on the input clock to my DCM is not being propagated through the DCM and the correct constraints are not being created on the outputs of the DCM. The PCF does not contain any of the constraints that should have been generated, nor does the Derived Constraints section of the timing report show the constraints.


To work around this issue, set the environment variable XIL_NGDBUILD_CS to "1".

If you have questions on how to set environment variables, please refer to (Xilinx Answer 11630).

This issue is scheduled to be fix in Service Pack 3 for ISE 10.1.
AR# 31566
Date 09/03/2008
Status Active
Type General Article