Keyboard and user guidance

 

on:	Switch on the device (press for at least 1 second)
off:	Switch off the device (press for at least 1 second)
start/centre:	Start measurement/entry into a menu, entry into a lower menu level if necessary
save:	Saving operating parameters
↑	Moving the cursor upwards or exiting a menu
↓	Moving the cursor downwards
→	Increasing a value or selecting a different operating state
←	Decreasing a value or selecting a different operating state

Note:
Depending on the menu or menu level, pressing buttons that are currently meaningless will display an explanation of the current menu status, i.e. a kind of help.