Connect to ch340 on MacOS Mojave
Ok, this is the solution for me: 

remove all old drivers:

sudo rm -rf /Library/Extensions/usbserial.kext
sudo rm -rf /System/Library/Extensions/usb.kext


Now reboot the computer.

And then (very important, because it took me 10 cables to find the right one) use a fully connected cable ;-) 

Now I have these ports: 

/dev/cu.wchusbserial1410
/dev/cu.usbserial-1410