MATLAB Discrete Event System — Extends System objects to create custom SimEvents blocks in your model. This capability is useful for including algorithms.
Discrete Event Chart — Uses Stateflow® charts and messages to create custom blocks in your model. This capability is useful for creating application-oriented blocks and add-on software. Examples of such software are real-time operating system schedules and communication networks.
With just SimEvents and its required software, you can implement your Discrete Event Chart custom block. However, to simulate the model you must have a Stateflow license.