Logging

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.

Another way to test a circuit is using a test vector. Logisim's test vector module allows you to load a file specifying circuit inputs and the values that should be output by the circuit. Logisim will run the simulation and compare the actual outputs against the desired outputs. Currently, test vectors are only designed to work for combinational circuits.

Note: The logging and test vector modules are in alpha phase; they may be buggy, and they are subject to significant changes in the future. While bug reports and suggestions are welcome for all of Logisim, they are particularly welcome concerning these relatively new features. If you do not send comments, then they will likely not change.

You can enter the test vector module via the Test Vector... option from the Simulate menu. See Test Vectors for documentation on how to use this module.

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.

The Selection tab
The Table tab
The File tab

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.