Device for controlling a washing machine

A device for controlling a washing machine, said device comprising:

• a filter device that is configured to be supplied with a washing liquid from the washing machine and that has a horizontally-arranged rotating screen drum, through which the washing liquid flows from an inside thereof to an outside thereof, and a discharge screw conveyor that is arranged inside the screen drum, below a vertex region thereof, and passes through the screen drum on an end face on a discharge side,
• a cleaning device with cleaning nozzles that are provided outside the screen drum, directed towards the screen drum and can be supplied with a pressurized medium;
• a level indicator outputting an output signal based on a level of the washing liquid in the screen drum;
• and
• a control device that controls either the washing machine or the cleaning device responsive to the output signal of the level indicator.