• Open a pre-configured project with a functional trend object.
• Create an auxiliar TAG (Boolean) as trigger (here named as "Trigger").
• HMI tag's definition: select the logged tag (here named as "HMI_Tag_1"), select "Logging tags" tab (between tag table and inspector window), change the follow properties:
  • logging mode = On demand
  • Trigger mode = any option else "none" (that means Rising edge, Falling edge, Rising and falling edge, here "Rising and falling edge")
  • Trigger tag = trigger signal (here "Trigger" tag)
• To control the trigger, drag & drop it form the symbol table to a screen.

Hello Seba68

the project is not empty there is a small examle in a WinCC Unified PC RT station:

Bye Murof