I have an Arduino Uno that I have installed shields on to control three Nema 17 stepper motors. I uploaded and executed the latest Arduino ide software and flashed it with the latest Grbl software. I sent a file to it using the OpenBuildsCONTROL-Setup-1.0.304. The Gcode file I sent draws a circle as it is designed to do. However when I try to jog the X, Y, or Z axis I get this message "Undefined J+91 G21 X1000". I am very new at this and really don't know what I am doing. Any ideas how to remedy this error message? Thanks, Ken
A screenshot of the error / extract of the serial log would be better for accuracy Are you sure its running Grbl 1.1? Rather flash using CONTROL > Wizards and Tools > Firmware Flashing tool to make sure you have Grbl 1.1 - as Grbl 0.9 didn't support $J commands, but 1.1 does.
That means you are running GRBL 0.9 which does not support jog commands. You need to flash GRBL 1.1, just use OBCONTROL to do it, much easier than setting up Arduino IDE for it.