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Task Overruns on EV3 Hardware

Standard scheduling works well when a processor is moderately loaded. When a processor becomes overloaded, the scheduler may run a task before the previous instance of the same task has completed. The result is a task overrun.

Enable Overrun Detection

You can configure a model running on the target hardware to notify you when a task overrun occurs.

  1. In the Modeling tab of the toolstrip, select Model Settings.

  2. In the Configuration Parameters dialog box, select the Hardware Implementation. Select the Detect task overruns check box.

  3. Click OK or Apply.

When a task overrun occurs, the EV3 display shows an “Overrun!” error message until you stop the model.

Fix Overrun Condition

The three recommended methods to fix a task overrun are to:

  • Simplify the model.

  • Increase the sample times for the model and the blocks in it. For example, change the Sample time parameter in all of your data sources or sensor blocks, from 0.1 to 0.2.

  • If you are using External mode, consider disabling External mode.


External mode increases the processing burden of the model running on the EV3 hardware. If the software reports an overrun, disable External mode.