An e-stop is a complement to, not a replacement for, the safeguards that prevent access in the first place. It exists for the moment something already went wrong and a person needs to stop the machine now.
Standards distinguish stop categories: category 0 removes drive power immediately, letting the robot coast or brake mechanically; category 1 uses a controlled braking ramp and then removes power, which is gentler on a heavy arm carrying a load. Category 2 keeps power on with motion stopped and is a protective stop rather than an emergency stop.
Buttons sit on the teach pendant, the control cabinet and around the cell. The circuit is built to a required safety level so that a single fault, a broken wire or a welded contact, cannot disable it silently.
