What is the functionality of the suction nozzles on the KM-ASSYM2-02 machine and how do they ensure safe operation?

Can you explain what the M125-Suction nozzles 1&2 have not reached the safe height error message means and why
The solution to the M125-Suction nozzles 1&2 have not reached the safe height error when the slide is running (PLC2-X0, X1) may involve adjusting the nozzle height