How to interrupt long command with G-code? I was able to connect my terminal program (Putty) to my 3D Printer (Creality Ender 3 Pro) and was able to send G-code commands to my printer and it obeys.
Now suppose I sent long command like
G29 ; auto bed leveling

and it is still executing. Printer writes me
echo:busy: processing

How to interrupt it?
I tried to send M0, but it didn't work.
3D Printers are pretty basic when it comes to g-code. There is no cycle start or cycle pause function on them. There is also no g-code command to interrupt the previous command. To get it to a halt you could turn it off. Or if the printer's firmware is configured to do so, you can touch one of the limit switches to get it to stop its movements.