$ 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 enables GRBL laser mode and is required for motion-synchronized dynamic-power M4 engraving. M3 remains constant-power output.
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 values produce tighter cornering but put more stress on the mechanics. Keep the current values or start from the machine manufacturer's specifications, change them gradually, and verify motion with controlled tests before relying on the result.
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:
$$
$30
$30=…$$lists all settings.$30queries a single setting.$30=…is a write template. Replace the ellipsis with the controller-specific value, and do not paste the line unchanged. A written value persists to EEPROM.
In Device Settings → GRBL Settings tab:
- Click any value to edit inline.
- Click Apply to Active Profile to copy a valid
$30into S-value Max and the lower valid rate from$110/$111into Max Speed. It does not copy every live setting.
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.