You have your shiny new DSL up and running thanks to the Eclipse Modeling Technologies and you built a powerful tooling with graphical modelers, textual syntaxes or dedicated editors to support it. But how can you see what is going on when a model is executed ? Don't you need to simulate your design in some way ? Wouldn't you want to see your editors being animated directly within your modeling environment based on execution traces or simulator results? The GEMOC Research Project designed a methodology to bring animation and execution analysis to DSLs. The companion technologies required to put this in action are small dedicated components (all open-source) at a "proof of concept" maturity level extending proven components : Sirius, Eclipse Debug, Xtend making such features within the reach of Eclipse based tooling. The general intent regarding those OSS technologies is to leverage them within different contexts and contribute them to Eclipse once proven strong enough. The method covers a large spectrum of use cases from DSLs with a straightforward execution semantic to a combination of different DSLs with concurrent execution semantic. Any tool provider can leverage both the technologies and the method to provide an executable DSL and animated graphical modelers to its users enabling simulation and debugging at an early phase of the design. This talk presents the approach, the technologies and demonstrate it through an example: providing Eclipse Debug integration and diagram animation capabilities for Arduino Designer (EPL) : setting breakpoints, stepping forward or backward in the execution, inspecting the variables states... We will walk you through the steps required to develop such features, the choices to make and the trade-offs involved. Expects live demos with simulated blinking leds and a virtual cat robot !