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FRC · LabVIEW

First Robotics Competition

FRC · LabVIEW

  • Motor Safety and Recovery

Motor Safety and Recovery

Use motor-safety timeouts and responsive loops to stop stale outputs.

Module 4: Safety and RecoveryWalkthrough

In this lesson, you will:

  1. 01Enable and explain a drivetrain safety timeout.
  2. 02Know which code path refreshes motor output.
  3. 03Recognize and recover from loop starvation.

Motor safety watches for stale commands

FRC LabVIEW includes drive and motor safety configuration VIs. When enabled, the safety system expects code to refresh an actuator before a short timeout; if updates stop, it forces the output off instead of holding the last command.

Bad loops look like robot lag

If a loop blocks or runs too slowly, driver control can feel delayed. Keep long waits out of Teleop and use explicit state instead.

Test the watchdog on blocks

Put the robot securely on blocks, enable a short safety timeout, and intentionally delay updates longer than that timeout. The drivetrain should stop. Remove the artificial delay afterward, then disable the robot during another low-power test and confirm that every output stops.

LabVIEW habit

Document the chosen safety timeout beside the configuration VI and test it at low power with the robot on blocks.

Easy mistake

Remove every artificial delay used to test starvation before deploying normal robot code.

LabVIEW diagram viewer

Block diagram walkthrough

Hover a VI. Press Ctrl-H for help.

Press enter or space to select a node. You can then use the arrow keys to move the node around. Press delete to remove it and escape to cancel.
Press enter or space to select an edge. You can then press delete to remove it or escape to cancel.
Block diagram walkthrough

Practice

On blocks at low power, enable drivetrain safety with a documented timeout. Add a temporary wait longer than the timeout, observe the automatic stop, then remove the wait and verify normal Teleop response.

Checks

  • The configured safety timeout is visible and documented in Begin.vi.
  • A deliberately starved update causes the drivetrain to stop before the test interval ends.
  • The temporary blocking wait is removed after the safety test.
  • Teleop responds immediately after normal code is restored.

Lesson check

Check your understanding before moving on.

When safety is enabled and drivetrain code stops refreshing output before the timeout, what happens?

Teleop feels laggy. What is the most likely cause in LabVIEW?

0 of 2 answered

References

WPILib LabVIEW DocsCurrent official FRC LabVIEW programming documentation.FRC LabVIEW ResourcesCurrent WPILib tutorials, examples, and troubleshooting resources.Recovering from bad loopsOfficial guide to LabVIEW drive and actuator safety timeouts.

Finished reading?

Mark this lesson complete.

Autonomous State Flow