Instruments are classes that are intended to inspect running models in some way. They are to be passive, in that they should have no influence on the model's behavior. Typically they are used for logging, tracking, or sending data to file.

Default Model Logger

This instrument intercepts the log messages and sends them to a named file. After the file reaches a maximum size, it is backed up. The number of backups can be configured. By default, this instrument attaches to all the models in the runtime. When configured programmatically, you can specify which log streams go to which file. In the IDE, all the streams go to a single file.


  • MaxFileSize: in megabytes before the file is backed up and a new file created.
  • NumberOfBackups: the number of backups to retain.
  • all: what filename to send all the streams to.

Model Recorder

Instrument that records the runtime's models at the start and stop of execution. The format of the saved models can be configured to use any of the installed syntaxes (e.g., jactr, lisp). The location of the files can also be specified.


  • SaveAsExtension : extension of the code generator to use. (default: jactr)
  • StartDirectory : local working directory path to save the start state models to. Will be created if missing. (default: start/)
  • StopDirectory : local working directory path to save the stop models to. Will be created if missing. (default: stop/)
  • TrimModuleContributions : Don't include the injected content from modules and extensions in the generated code. (default: true).

Runtime Throttler

Whether you are tracing or trying to be nice to other programs, sometimes models just run too fast. The runtime throttler allows you to specify a minimum real cycle time for the models. If the model runs too on that cycle, the model thread will be put to sleep for the remainder of the time. The default value of MinimumCycleRealTime is 0.05, i.e. real time.

XML Model Logger

An alternative logger that routes messages to an xml file. This logger attaches to all the models in the runtime.


  • FileName : the xml file to save to.