A stop function which has all of the following requirements:

  • It shall override all other functions and operations in all modes.
  • Power to machine actuators that can cause a hazardous condition (s) shall be removed as quickly as possible without creating other hazards (e.g., by the provision of mechanical means of stopping requiring no external power, by reverse current braking for a Category 1 stop).
  • Reset shall not initiate a restart.
  • The emergency stop shall function as either a Category 0 or Category 1 stop.

The choice of category of emergency stop shall be determined in accordance with the requirements of the application.

  • Where a Category 0 stop is used for the emergency stop function, it shall have only hardwired electromechanical components. In addition, its operation shall not depend on electronic logic (hardware or software) or the transmission of commands over a communication network or link.
  • Where a Category 1 stop is used for the emergency stop function, final removal of power to the machine actuators shall be ensured and shall be by means of electromechanical components.