How do I operate a ZWave thing found in the DB, but no with channels (Remotec ZXT-310)?

It is not. The XML will be overwritten.

I don’t understand, have you modified what you posted?

Edit: If you want to play here is the current file in the binding
zxt310_0_0.xml (3.2 KB)
. You can make changes and add it to the binding following this procedure. Update ZWave binding with new/updated device xml - Tutorials & Examples - openHAB Community