Glossary · Stopping functions and safe states
Stop category 2
Under IEC 60204-1, stop category 2 is a controlled stop with power remaining available to the machine actuators. The machine is stopped but energized and can resume motion without re-energizing.
- Machine safety
- Risk assessment
In one sentence
Stop category 2 stops the machine under control and keeps actuator power on. It is not permitted for emergency stop.
Example
A CNC machining center pauses its axes in stop category 2 when the operator presses feed hold; the axes stay under position control, monitored by Safe Operating Stop.
How it applies
- Machine safety: Because power remains, a fault can restart motion. If people are exposed during the stop, the standstill must be monitored, for example with Safe Operating Stop, and unintended restart must be prevented.
- Emergency stop: Stop category 2 cannot be used for an emergency stop; only categories 0 and 1 are permitted.
- Technical documentation: Do not describe a category 2 stop as “switched off”. Users must know that the machine is energized and which actions are allowed while it is stopped.
- Evidence: Record which stop functions use category 2 and the risk assessment that justifies it.
Stop category 2 vs. stop category 0
Stop category 0 removes power immediately. Category 2 keeps it, which allows fast restart and holding position, at the cost of energized actuators.