Xilinx Constraints Guide

Chapter 4: Xilinx Constraints
The following statement assigns an IFD_DELAY_VALUE increment of 5 to the net
DataIn1:
attribute IFD_DELAY_VALUE : string;
attribute IFD_DELAY_VALUE of DataIn1: label is "5";
Verilog Syntax
Attach a Verilog attribute to the appropriate top-level port.
(* IFD_DELAY_VALUE="value" *) input top_level_port_name;
The following statement assigns an IFD_DELAY_VALUE increment of 5 to the net
DataIn1:
(* IFD_DELAY_VALUE="5" *) input DataIn1;
UCF and NCF Syntax
NET "top_level_port_name" IFD_DELAY_VALUE = value;
value is the numerical IBUF delay setting
The following statement assigns an IFD_DELAY_VALUE increment of 5 to the net
DataIn1:
NET "DataIn1" IFD_DELAY_VALUE = 5;
Constraints Guide
136 www.xilinx.com UG625 (v. 13.2) July 6, 2011