Why is the “ON” LED of the power supply red and flashing on a 1038/20?

Fault:

The “ON” led of the power supply is red flashing.

Solution: 

Check all power supply units in the system, only one must be set as “MASTER” (jumper M1-M2). Check the terminal “DE” of “MASTER” power supply, as this terminal must not be used in this power supply unit.