In ISE Simulator, the waveform data is saved as a .wdb file automatically.
However, when a new simulation is run, the .wdb file from the last run will be overwritten.
To save the current waveform for later use, follow these steps:
1. Rename the .wdb file or copy it to another location other than the project directory.
2. To view the saved waveform in ISE Simulator, use either of the following command lines.
isimgui.exe -view xxx.wdb
isimgui.exe -open xxx.wdb -view xxx.wcfg
The xxx.wcfg file is the waveform configuration file if you have one for the .wdb file.
Note: Currently you cannot view the waveform by selecting "File -> Open" and then the .wdb file directly in ISE Simulator GUI.
Running the command line is the only way to view the waveform.
For more information on .wdb and .wcfg files, please refer to the UG660-ISIM User Guide at http://www.xilinx.com/support/documentation/dt_ise.htm