Ecercise 4: Barrier


Using the example of an (articulated arm) barrier, the model introduces the control of end positions. End position switching is taken up again in models 5 and 6. The light barrier from model 3 is used as a demand switch. The model is supplemented by a voice output in the experimental task.


Motor control and end position stop, speech output.



Learning objective

  • Design and programming of an end position stop
  • Use of a light barrier as a demand switch
  • Introduction of logical operators (“NOT”)
  • Programming voice output in Scratch

Time required

Setting up and programming the barrier for the first time takes about two lessons. The other tasks build directly on each other and take about one lesson. It makes sense to repeat the programming of the alarm system from model 3 to process the programming tasks for the demand barrier with warning light. The experimental task enables individualization of the barrier program; it is not required for the following task 
sheets, but is well suited as a final task.

Note: The voice output in the experiment output requires the computer to be connected to the Internet.