| $0 | Step pulse time | 10 | microseconds | Sets time length per step. Minimum 3usec. |
| $1 | Step idle delay | 25 | 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 | 4 | 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 | 0.010 | 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 | 0 | boolean | Enables hard limits. Immediately halts motion and throws an alarm when switch is triggered. |
| $22 | Homing cycle enable | 0 | boolean | Enables homing cycle. Requires limit switches on all axes. |
| $23 | Homing direction invert | 0 | mask | Homing searches for a switch in the positive direction. Set axis bit (00000ZYX) to search in negative direction. |
| $24 | Homing locate feed rate | 25.000 | mm/min | Feed rate to slowly engage limit switch to determine its location accurately. |
| $25 | Homing search seek rate | 500.000 | mm/min | Seek rate to quickly find the limit switch before the slower locating phase. |
| $26 | Homing switch debounce delay | 250 | milliseconds | Sets a short delay between phases of homing cycle to let a switch debounce. |
| $27 | Homing switch pull-off distance | 1.000 | 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. |
| $43 | | 0 | | |
| $44 | | 0 | | |
| $45 | | 5 | | |
| $46 | | 0 | | |
| $51 | | 8192 | | |
| $52 | | 1000066 | | |
| $53 | | 578617871 | | |
| $54 | | 1558940235 | | |
| $55 | | 1000380 | | |
| $56 | | 1421796994 | | |
| $57 | | 183703318 | | |
| $58 | | 1968007489 | | |
| $59 | | 6906216 | | |
| $60 | | 0 | | |
| $61 | | 0 | | |
| $100 | X-axis travel resolution | 800.000 | step/mm | X-axis travel resolution in steps per millimeter. |
| $101 | Y-axis travel resolution | 800.000 | step/mm | Y-axis travel resolution in steps per millimeter. |
| $102 | Z-axis travel resolution | 800.000 | step/mm | Z-axis travel resolution in steps per millimeter. |
| $103 | | 50000.000 | | |
| $104 | | 50000.000 | | |
| $105 | | 3200.000 | | |
| $110 | X-axis maximum rate | 2000.000 | mm/min | X-axis maximum rate. Used as G0 rapid rate. |
| $111 | Y-axis maximum rate | 2000.000 | mm/min | Y-axis maximum rate. Used as G0 rapid rate. |
| $112 | Z-axis maximum rate | 500.000 | mm/min | Z-axis maximum rate. Used as G0 rapid rate. |
| $113 | | 500.000 | | |
| $114 | | 500.000 | | |
| $115 | | 500.000 | | |
| $120 | X-axis acceleration | 10.000 | mm/sec^2 | X-axis acceleration. Used for motion planning to not exceed motor torque and lose steps. |
| $121 | Y-axis acceleration | 10.000 | mm/sec^2 | Y-axis acceleration. Used for motion planning to not exceed motor torque and lose steps. |
| $122 | Z-axis acceleration | 10.000 | mm/sec^2 | Z-axis acceleration. Used for motion planning to not exceed motor torque and lose steps. |
| $123 | | 10.000 | | |
| $124 | | 10.000 | | |
| $125 | | 10.000 | | |
| $130 | X-axis maximum travel | 200.000 | 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 | 200.000 | 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 | 200.000 | millimeters | Maximum Z-axis travel distance from homing switch. Determines valid machine space for soft-limits and homing search distances. |
| $133 | | 200.000 | | |
| $134 | | 200.000 | | |
| $135 | | 200.000 | | |