@dc42
I removed the diodes and the NPN Sensors are working properly now.
Thanks all for your help.

@dc42
I connected microswitches to X and Y now, so I can run my first print. They are both working.
I already connected the ground wire to the input of the endstop but it also didn't work.

I did some troubleshooting this morning. I connectet the X-Sensor to the Z-input and could stop the Z-axis with a piece of metal holding it to the X-Sensor. Same with the Y-Sensor. That tells me that the sensors work fine.
Then I connectet Z-Motor and Sensor to the Y-connectors on the duet. The LED triggered but the motor did not stop. M119 says Y-Axis homed.
Is it possible that there is a problem with the board?
Or does anyone have an idea?

@dc42
I connected 24V and Ground to the Power Supply.

@droftarts
hmm, the micro switch is working in X and Y.
The Sensors are MLM8-3002NA NPN, Schließer.
24 V and a BAT43 Diode at the signal output.
Why does the z-axis work? Its all the same setup.

I have to leave now. Thank you all for your answers, if there are any ideas whalt I can di to get those sensors working, I`ll try tomorrow.

@dc42
once again the homex.g file:

; homex.g
; called to home the X axis
;
; generated by RepRapFirmware Configuration Tool v2.1.2 on Mon Nov 11 2019 14:44:06 GMT+0100 (Mitteleuropäische Normalzeit)
G91 ; relative positioning
G1 H2 Z5 F1800 ; lift Z relative to current position
G1 H1 X-395 F1800 ; move quickly to X axis endstop and stop there (first pass)
G1 X5 F1800 ; go back a few mm
G1 S1 X-395 F360 ; move slowly to X axis endstop once more (second pass)
G1 H2 Z-5 F1800 ; lower Z again
G90 ; absolute positioning

I tried to home X and triggered both, X and Y Endstop. No reaction

@dc42
thanks for answering,
I tried M119 serveral times for each axis, it always shows if triggered or not.
the endstops are not swapped and the movement goes to the correct direction.

@droftarts

Here it is:

G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P"Olli3" ; set printer name

M669 K1 ; switch to CoreXY mode

; Network
M552 S1 P172.21.163.110 ; enable network
M553 P255.255.255.0
M554 P 172.21.163.2

M586 P0 S1 ; enable HTTP
M586 P1 S0 ; disable FTP
M586 P2 S0 ; disable Telnet

; Drives
M569 P0 S0 ; physical drive 0 goes forwards
M569 P1 S0 ; physical drive 1 goes forwards
M569 P2 S1 ; physical drive 2 goes backwards
M569 P3 S0 ; physical drive 3 goes forwards
M584 X0 Y1 Z2 E3 ; set drive mapping
M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation
M92 X32.00 Y32.00 Z640.00 E460.00 ; set steps per mm
M566 X900.00 Y900.00 Z12.00 E120.00 ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00 ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00 ; set accelerations (mm/s^2)
M906 X1600 Y1600 Z500 E500 I30 ; set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Axis Limits
M208 X0 Y0 Z0 S1 ; set axis minima
M208 X390 Y290 Z100 S0 ; set axis maxima

; Endstops
M574 X1 Y1 Z2 S0 ; set active high endstops

; Z-Probe
M558 P0 H5 F120 T6000 ; disable Z probe but set dive height, probe speed and travel speed
M557 X15:215 Y15:195 S20 ; define mesh grid

; Heaters
M140 H-1 ; disable heated bed
M305 P1 T100000 B4725 C7.060000e-8 R4700 ; set thermistor + ADC parameters for heater 1
M143 H1 S280 ; set temperature limit for heater 1 to 280C

; Fans
M106 P0 S0 I0 F500 H-1 ; set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
M106 P1 S1 I0 F500 H1 T45 ; set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on

; Tools
M563 P0 D0 H1 F0 ; define tool 0
G10 P0 X0 Y0 Z0 ; set tool 0 axis offsets
G10 P0 R0 S0 ; set initial tool 0 active and standby temperatures to 0C

; Custom settings are not defined

; Miscellaneous
M911 S20 R22 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; set voltage thresholds and actions to run on power loss

@Veti
I did so. After G1 H1 X-395 F1800 it crashed.

@deckingman
I changed everything as you wrote. It still crashes into the frame.