Glossary · Protective devices and interlocks
Reset function
Also known as: reset
German: Rücksetzen
In machine safety, a reset function is a deliberate action that restores readiness after a protective function has been triggered. Reset must not initiate hazardous motion; a separate start command is needed.
- Machine safety
- Human factors
In one sentence
A reset function restores readiness after a safety stop, but must never start the machine itself; restart always requires a separate start command.
Example
After an emergency stop on a packaging line, the operator releases the emergency stop button, presses the blue reset button and then presses start to resume.
How it applies
- Machine safety: Reset separates “safe to start” from “start”. Combining the two in one button creates an unexpected startup risk.
- Design: Reset should only be possible when the triggering condition has been cleared, for example the guard is closed or the emergency stop device released. Automatic reset may be acceptable only where nobody can remain undetected in the hazard zone.
- Systems engineering: Reset is a state transition in the machine's state model. Specify which states allow reset and what the machine does afterward.
- Technical documentation: Describe the full recovery sequence after each type of safety stop, in the order the operator must follow it.
Reset function vs. restart prevention
The reset function is the action that restores readiness. Restart prevention is the function that ensures motion does not resume automatically.