$ settings reference
Every GRBL $ setting with a one-line description and the laser-specific guidance for each.
The full list of GRBL $ settings. For each, a one-line summary and (where relevant) the laser-specific guidance.
For an interactive view that loads the current values from your machine, use Device Settings → GRBL Settings tab.
Step pulse and direction
| Setting | Meaning | Typical |
|---|---|---|
$0 | Step pulse, microseconds | 10 |
$1 | Step idle delay, ms (255 = always-on) | 25 or 255 |
$2 | Step port invert mask | 0 (most setups) |
$3 | Direction port invert mask | depends on motor wiring |
$4 | Step enable invert | 0 |
$5 | Limit pins invert | depends on switch type |
$6 | Probe pin invert | 0 |
Reporting and behavior
| Setting | Meaning | Typical |
|---|---|---|
$10 | Status report mask | 1 or 2. Beam Bench parses both |
$11 | Junction deviation (mm) | 0.010 |
$12 | Arc tolerance (mm) | 0.002 |
$13 | Report inches (1=yes, 0=mm) | 0 |
Safety and limits
| Setting | Meaning | Typical |
|---|---|---|
$20 | Soft limits enable | 0 or 1 |
$21 | Hard limits enable | 0 or 1 |
$22 | Homing cycle enable | 0 or 1 |
$23 | Homing direction mask | depends on home corner |
$24 | Homing feed (mm/min) | 25 |
$25 | Homing seek (mm/min) | 500 |
$26 | Homing debounce, ms | 250 |
$27 | Homing pull-off (mm) | 1 |
Laser specifics
| Setting | Meaning | Typical |
|---|---|---|
$30 | Maximum spindle / laser S value | 1000 or 255 |
$31 | Minimum spindle / laser S value | 0 |
$32 | Laser mode (1=on, 0=off) | 1 for laser engraving |
$32=1 is non-negotiable for laser engraving, it synchronizes power with motion.
Axis steps/mm
| Setting | Meaning |
|---|---|
$100 | X steps/mm |
$101 | Y steps/mm |
$102 | Z steps/mm |
Specific to your machine. See Steps per millimeter.
Max rates (mm/min)
| Setting | Meaning |
|---|---|
$110 | X max rate |
$111 | Y max rate |
$112 | Z max rate |
Set to your machine's safe maximum. Going beyond will stall motors.
Acceleration (mm/sec²)
| Setting | Meaning |
|---|---|
$120 | X acceleration |
$121 | Y acceleration |
$122 | Z acceleration |
Higher = tighter cornering. Diode laser: 1000-3000 is reasonable. CO2 gantry: 500-1500.
Maximum travel (mm)
| Setting | Meaning |
|---|---|
$130 | X max travel |
$131 | Y max travel |
$132 | Z max travel |
Used for soft limits ($20=1). Set to your physical bed dimensions.
Reading and writing
In the Console panel:
$$ # dump all settings
$30 # query a single setting
$30=1000 # set a setting (persists to EEPROM)In Device Settings → GRBL Settings tab:
- Click any value to edit inline.
- Click Apply to Active Profile to copy live values into the machine profile.
Resetting
Send $RST=$ to reset all $ settings to firmware defaults. Send $RST=# to reset coordinate offsets. Send $RST=* to reset everything. Use with caution, your tuning vanishes.
Per-firmware variations
- GRBL_ESP32 adds some settings around WiFi, BlueTooth, web UI.
- FluidNC uses a YAML config file instead of
$settings for most things (but some$settings still apply). - Older GRBL versions may be missing some of the above.
When in doubt: send $$, see what your controller actually reports.