It is possible, to upload the hmi/tft-file via the serial interface?
My Nextion Display ist connect to a Raspberry Pi. It is very disadvantageous to use the "direct" way from the Windows Computer where the Editor is installed, also to do it with the micro sd, because the Display is build in...
Is there a way, to "send" the new hmi/tft-file over the Serial Interface?
Yes it is possible.
Itead published the upload specs for this in their blog. (See Itead Studios Blog)
You would still need to transfer the TFT file over to the Raspberry Pi, and then have the Pi do the upload that the Nextion Editor would have been doing. The coding for such would be up to you to accomplish, test, debug etc.
it took a little time, but now it works!