Should fixed-point numbers be displayed? The "Display" block in the Xilinx block set does not accept fixed-point numbers directly as input.
You must output your data through a gateway out, then to the "Display" block or to a "Scope".
Another solution would be to use the Simulink "To Workspace" blocks to save values to the Matlab workspace, where it can then be inspected visually. You may also use the "To File" block.