Sealing and ContactSafe Motor Switching

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What You Need to Know Before Design

  • AND
  • NOT
  • OR
  • Adding a Line Label

Diagram Algorithm

  • When the button is pressed forward, the motor will start to move forward and the button will continue even if it is not pressed forward.
  • When the button is pressed back the engine will stop and immediately the engine will start to run in reverse direction.
  • If two buttons are pressed at the same time, the system will stop.

Diagram Solution


  • In the sealing algorithm, the 'motor forward' will start to work when the high signal is applied via 'forward button'. The 'motor forward' label will produce a high level output when the 'motor forward' starts to work and the 'motor forward' will be active even if the button is not pressed.
  • In the safety algorithm, the two buttons pressed together condition is checked. Binary flag is used to generate a 1 cycle delay in button controls.
  • In the above picture there is an online monitoring screen image where the button is pressed forward, the motor is forward activated and the 2 buttons in the picture below are pressed together so that the motor's forward and reverse outputs are inactive.