Error (10386): VHDL error : non-constant index is always outside the range

Hello,

I could reproduce your problem and found a possible solution.

You might want to check the indexes, but the basic idea is shown below.

architecture rtl of DE10_STD_FORUM is
 
constant N_BITS : integer:=8;
	 
-- declare --
 signal test_incomingMessage  : std_logic_vector (N_BITS-1 downto 0):= (others=> '0');
 signal aux_incomingMessage   : std_logic_vector ((512*N_BITS)-1 downto 0):= (others=> '0');
 
 
begin
 
-- body --
	process (CLOCK2_50)
	 variable count                 : integer:= 1;
	 variable index                 : natural range 4096 downto 0;
	begin
		if rising_edge(CLOCK2_50) then
			if count < 513 then
					index:=count*N_BITS;
					aux_incomingMessage(index-1 downto index-N_BITS)<= test_incomingMessage;
					count:= count + 1;
			end if;
		end if;
	end process;
end rtl;

Best Regards,

Johi.