$0	Step pulse time	20	microseconds	Sets time length per step. Minimum 3usec.
	$1	Step idle delay	50	milliseconds	Sets a short hold delay when stopping to let dynamics settle before disabling steppers. Value 255 keeps motors enabled with no delay.
	$2	Step pulse invert	0	mask	Inverts the step signal. Set axis bit to invert (00000ZYX).
	$3	Step direction invert	1	mask	Inverts the direction signal. Set axis bit to invert (00000ZYX).
	$4	Invert step enable pin	0	boolean	Inverts the stepper driver enable pin signal.
	$5	Invert limit pins	0	boolean	Inverts the all of the limit input pins.
	$6	Invert probe pin	0	boolean	Inverts the probe input pin signal.
	$10	Status report options	1	mask	Alters data included in status reports.
	$11	Junction deviation	0,050	millimeters	Sets how fast Grbl travels through consecutive motions. Lower value slows it down.
	$12	Arc tolerance	0,002	millimeters	Sets the G2 and G3 arc tracing accuracy based on radial error. Beware: A very small value may effect performance.
	$13	Report in inches	0	boolean	Enables inch units when returning any position and rate value that is not a settings value.
	$20	Soft limits enable	0	boolean	Enables soft limits checks within machine travel and sets alarm when exceeded. Requires homing.
	$21	Hard limits enable	1	boolean	Enables hard limits. Immediately halts motion and throws an alarm when switch is triggered.
	$22	Homing cycle enable	1	boolean	Enables homing cycle. Requires limit switches on all axes.
	$23	Homing direction invert	7	mask	Homing searches for a switch in the positive direction. Set axis bit (00000ZYX) to search in negative direction.
	$24	Homing locate feed rate	600,000	mm/min	Feed rate to slowly engage limit switch to determine its location accurately.
	$25	Homing search seek rate	3000,000	mm/min	Seek rate to quickly find the limit switch before the slower locating phase.
	$26	Homing switch debounce delay	100	milliseconds	Sets a short delay between phases of homing cycle to let a switch debounce.
	$27	Homing switch pull-off distance	2,000	millimeters	Retract distance after triggering switch to disengage it. Homing will fail if switch isn't cleared.
	$30	Maximum spindle speed	1000	RPM	Maximum spindle speed. Sets PWM to 100% duty cycle.
	$31	Minimum spindle speed	0	RPM	Minimum spindle speed. Sets PWM to 0.4% or lowest duty cycle.
	$32	Laser-mode enable	1	boolean	Enables laser mode. Consecutive G1/2/3 commands will not halt when spindle speed is changed.
	$33		250,000		
	$100	X-axis travel resolution	80,000	step/mm	X-axis travel resolution in steps per millimeter.
	$101	Y-axis travel resolution	80,000	step/mm	Y-axis travel resolution in steps per millimeter.
	$102	Z-axis travel resolution	80,000	step/mm	Z-axis travel resolution in steps per millimeter.
	$110	X-axis maximum rate	9000,000	mm/min	X-axis maximum rate. Used as G0 rapid rate.
	$111	Y-axis maximum rate	9000,000	mm/min	Y-axis maximum rate. Used as G0 rapid rate.
	$112	Z-axis maximum rate	9000,000	mm/min	Z-axis maximum rate. Used as G0 rapid rate.
	$120	X-axis acceleration	2200,000	mm/sec^2	X-axis acceleration. Used for motion planning to not exceed motor torque and lose steps.
	$121	Y-axis acceleration	1800,000	mm/sec^2	Y-axis acceleration. Used for motion planning to not exceed motor torque and lose steps.
	$122	Z-axis acceleration	2500,000	mm/sec^2	Z-axis acceleration. Used for motion planning to not exceed motor torque and lose steps.
	$130	X-axis maximum travel	160,000	millimeters	Maximum X-axis travel distance from homing switch. Determines valid machine space for soft-limits and homing search distances.
	$131	Y-axis maximum travel	150,000	millimeters	Maximum Y-axis travel distance from homing switch. Determines valid machine space for soft-limits and homing search distances.
	$132	Z-axis maximum travel	1,000	millimeters	Maximum Z-axis travel distance from homing switch. Determines valid machine space for soft-limits and homing search distances.