Newbie with limited programing knowledge. I'm receiving the following error message "echo:Unknown command" with M226. Marlin 2.1.1 Pronterface Arduino Mega Ramps 1.4 Project: Syringe pumps actuated by stepper motors, which is activated by a digital signal loop. Briefly, when I use Marlin's command M226 to activate the pumps/motors from Pronterface command line, the error message "echo:Unknownby Adrianjay - Firmware - Marlin