Unknown firmware protocol

Rejdok

Hello! What kind of protocol(marlin, repetier, smoothie, etc.)  repetier host used if firmware type unknown? And can I add own protocol with plugins?

Repetier

Normally it goes back to default reprap protocol like used in marlin.

And no, you can not add own protocols with plugins. At least not easily. You would need to write a own connector that uses your special translation between gcode and reprap format.