# How do I save a waveform from ModelSim for later opening/viewing

If I save the waveform, it is saved as a .do file in ModelSim/QuestaSim. This does not help as later I will have to run the simulation to get the wave back anyway!

What I am looking for is means by which all the wave (their data at points in time) is saved in a single file like an EVCD file. Later I can just open this file even when I have absolutely nothing from the design itself and be able to pan and zoom in/out on the wave. I find nothing in ModelSim that can be used to do this. Saving the waveform as an image takes away a lot of important features, this is what I do at present but want to know how to save the wave itself for later use in the wave editor???

• It might save it as an ascii text file but to view the data you'd have to use a spreadsheet like excel. – Andy aka Oct 1 '13 at 11:38
• that is quite bizzare. If the tool can generate waveform for viewing, why can't we save and open it later without having to redo the whole simulation (after compiling everything)? This really does not make sense to me, it never has and never will. – quantum231 Oct 1 '13 at 12:28
• The amount of data shown on the screen is usually a tiny fraction of the complete data set - the simulation generates the data file and then it follows your guidance for which part of the whole picture you are trying to view. This is why it doesn't save some kind of jpeg. – Andy aka Oct 1 '13 at 12:30

You need to save the waveform/dataset as a .wlf file. To tell Modelsim to capture all signal values in the design you can do a log -r /*. Afterwards you can open up the specific waveform/dataset .wlf either through the GUI or by typing vsim -view <some_name>.wlf in the console. Have a look in the ModelSim/QuestaSim user manual under 'Saving a Simulation to a WLF File'