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AR# 14377

XST - "ERROR:HDLParsers:1015 - file_name.vhd Line xx. 'Wait for' statement unsupported"


Use of the "wait for" statement in VHDL is unsupported for synthesis in XST. 


For example, given the following: 


process begin
if clk'event and clk = '1' then 
data_out <= data_in; 
wait for 10 ns; -- not supported VHDL statement 
end if; 
end process; 


XST reports the following error: 


"ERROR:HDLParsers:1015 - file_name.vhd Line xx. 'Wait for' statement unsupported."


To avoid this problem, ensure that the VHDL code you are synthesizing is not a behavioral model; if it is not, remove the "wait for" statement. 


If it is a behavioral model, then do not try to synthesize it. 

XST is a synthesis tool and not a simulator.  


If this code is supposed to be used for both synthesis and simulation, Xilinx recommends putting them in two different files, one for synthesis and the other for simulation.

AR# 14377
Date Created 08/29/2007
Last Updated 05/12/2014
Status Active
Type General Article
  • ISE
  • ISE Design Suite