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AR# 3611

NGDBUILD: "logical block" of type 'DFFRSE' is unexpanded with a Synplify netlist


Problem description: Ngdbuild issues a warning on a behaviorally

described asynchronous set/reset regesiter with clock enable

warning basnu:93-logical block 'rebk1' of type 'DFFRSE' is unexpanded.


Synplify will infer a DFFRSE to describe an asynchronous set/reset

register with clock enable. However, the DFFRSE is not a valid

Xilinx primitive. Earier versions of Synplify have this problem.

Version 3.0c1 and above correct the problem by inferring a DFFRS.

The generic DFFRSE is no longer generated for 9500 series devices.

The DFFRS is also not a Xilinx primitive. See (Xilinx Solution 3486)

However, Synplicity provides the XNF netlist of the DFFRS. Make sure

you either source the directory with '-sd' option in Ngdbuild, or copy

the appropriate XNF file to your project directory so M1 could see the

files. These XNF netlists are located in the C:\synplcty\lib\xilinx

directory on the PC, and $SYNPLICITY/lib/xilinx on the WS.

You will need to upgrade to a more recent version of Synplify from



AR# 3611
Date Created 08/21/2007
Last Updated 05/14/2014
Status Archive
Type General Article