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Chrona TDL Component Model

A TDL-based Chrona component is a self-contained, reusable unit or module that governs one or more time-dependent task functions.



A TDL-based Chrona component consists of sensors, actuators and modes.

  • A mode is a set of periodically executed activities
  • These activities include task invocations, actuator updates and mode switches
  • All activities can have their own rate of execution. Further, all activities can be executed conditionally
  • Tasks are the functionality, typically implementing control laws


Actuator updates and mode switches transpire much faster than task invocations. For this reason, they are treated as taking place in logical zero time. In contrast, slower task invocations are expressed with the Logical Execution Time (LET) semantics.


Note: Any suitable language can be chosen to implement the functionality. If MathWorks’ tools are used, the functionality will be modeled in Matlab®/Simulink®.