Safety in automated machines
Also available in: Català · Castellano
Emergency stop (E-stop)
A big red mushroom-head button that stops the whole cell. It must be easy to find and to press. Next to it there is a TEST button for function checks.
Safety light curtains
They form an invisible fence around the warehouse manipulator. If someone enters, the signal changes and the PLC stops the servomotors.
Signal tower
| Colour | Meaning |
|---|---|
| Green | The cell is running |
| Amber | Warnings |
| Red | Stop or alarm |
Reset
After an alarm, the servomotors don’t start moving again on their own: they have to be reset from the panel (RSET, ALARM, SERVO and the ON selector). That way a person has to check that everything is safe before carrying on.
Interactive demo
Related concepts
PLC and GRAFCET
A PLC cyclically reads all its inputs, runs the program and updates the outputs. GRAFCET describes the process as a sequence of steps and transitions: each step waits for a condition before moving to the next.
X-Y Cartesian manipulator and servomotors
Two perpendicular axes driven by servomotors with encoders. At start-up it finds the zero of each axis; then it converts coordinates in millimetres into pulses to reach each position exactly.