Where can i find the device descriptor for the DSE device?

DSE files are contained in a single package that you can download from the DSE website. 

What is the default IP address of my device?

The default IP is static Make sure you verify that there are no other devices in the same network using the same IP and that you are in the same subnet.

CODESYS can find my device but I am unable to download start/stop/remove the application.

Check that the program enable is connected or that the debug mode is active.

CODESYS shows an error of version mismatch when I try to connect to my device.

Scan the device and check that the target version of the online controller is the same as the version of the device within your project.

When I try to compile I get an error about missing libraries.

Verify that you have installed the DSE package and that the version of CODESYS is 3.5 SP7 Patch 2. Alternatively you can use the function 'Download Missing Libraries' within the Library Manager.