In testing a large circuit, and for documenting a circuit's behavior, a log of past circuit behavior can be useful. This is the purpose for Logisim's logging module, which allows you to select components whose values should be logged; optionally, you can specify a file into which the log should be placed.
You can enter the logging module via the Logging... option from the Simulate menu. It brings up a window with three tabs.
We will discuss each of these tabs separately.
Each project has only one logging window; when you switch to viewing another circuit within the project, the logging window switches automatically to logging the other circuit instead. That is, it does this unless you are moving up or down within the same simulation, in which case the logging module does not change.
Note that when the logging module switches to logging another simulation, it will cease any logging into a file. Should you switch back to the simulation again, it will remember the configuration for that simulation, but you will need to re-enable the file logging manually.
Next: The Selection tab.