Simulator assignments

[Altera_Forum]

Hi, 

I try to simulate a design with the QuartusII simulator. Some of the signals are however synthesised away. I connect the signals to output pins and use the "Implement as Output of Logic Cell", "Add to Simulation Output Waveforms" and "Preserve Fan-out Free Register Node". Does the signal have to be available at top-level in order to preserve the signal during simulation? It is test-signals on lower-level blocks, so I dont want to append the signal to the top-level.  Hope someone can help.  Regards, Morten

[Altera_Forum]

"Preserve Fan-out Free Register Node" should be all you need (no need to route the signal to the top level) if you are using a device family supported by this assignment. 

  From QII 7.2 on-line help:    --- Quote Start ---  Preserve Fan-out Free Register Node logic option   -------------------------------------------------------------------------------- This option can be set in the Assignment Editor.    A logic option that specifies that the register should be preserved in the design even when it becomes fan-out free.  This option is available for supported device (Arria GX, Cyclone II, Cyclone III, HardCopy II, MAX II, Stratix II, and Stratix III) families.  --- Quote End ---  

[Altera_Forum]

I have tried to put output pins on the lower-level blocks and set the Preserve Fan-out Free Register Node logic option without any luck. I also tried to look in the RTL viewer for the signal and assign the same option, but still the signals are no where to be found in the simulator. 

I can only see them if I set the search option to "All name", but when I run the simulator they keep disappearing.  Any thoughts?

[Altera_Forum]

--- Quote Start ---  I have tried to put output pins on the lower-level blocks and set the Preserve Fan-out Free Register Node logic option without any luck.  --- Quote End ---     It should not matter whether the signal you want to preserve goes to an output port of an entity/module. It is necessary that the signal be a register.

[Altera_Forum]

Now I found the problem. I mostly uses VARIABLES, but in order to use Preserve Fan-out Free Register it has to be SIGNALS. 

 Thanks for the help.