You can configure a model running on the target hardware to detect and notify you of when task overrun occurs.
Standard scheduling works well when a processor is moderately loaded but may fail if the processor becomes overloaded. When a task is required to perform extra processing and takes longer than normal to execute, it may be scheduled to execute before a previous instance of the same task has completed. The result is a task overrun.
To enable overrun detection:
In your model, click Tools, Run on Target Hardware and Options.
In the Run on Target Hardware pane that opens, select the Enable overrun detection check box.
When a task overrun occurs, the LCD on the NXT brick displays an "Overrun!" error message until you stop the model.
To fix an overrun condition:
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, such as the sensor blocks, from 0.1 to 0.2.