V1 Setting V2 Setting Description

Whether to activate the laser module at all. The laser module is used for laser cutting using a laser diode or CO2 laser tube.

When set to `false`, all configuration is ignored and the module is completely unloaded to free system resources.

Must be enabled before any other laser settings take effect.

This pin controls the laser. Pulse width is modulated (PWM) to vary power output — PWM duty cycle directly controls laser power output percentage. This is the preferred and more descriptive parameter for specifying the PWM control pin for the laser.

CRITICAL: Only hardware PWM pins are supported:

  • 2.0 to 2.5
  • 1.18, 1.20, 1.21, 1.23, 1.24, 1.26
  • 3.25 and 3.26

Using non-PWM pins will disable the laser module with an error message. Inverting pin logic with the `!` prefix is useful for some laser driver circuits that are active-low.

DEPRECATED: Legacy parameter that specifies the pin controlling the laser through PWM. Superseded by for improved clarity.

If this pin is not connected, the system will check instead. Only specific pins on the Smoothieboard support the hardware PWM required for laser control.

Use for all new configurations.

This pin turns on when the laser turns on, and off when the laser turns off — a simple on/off signal synchronized with laser firing, independent of the PWM power level. This is a digital on/off signal, NOT PWM: it is either high or low.

Commonly used to:

  • Enable/disable air assist compressors
  • Enable/disable fume extraction fans
  • Drive laser power supply enable pins for additional safety
  • Drive safety interlocks that monitor when the laser is active

The maximum duty cycle that will be applied to the laser, as a value from `0` to `1`. Acts as both a safety limit and a calibration parameter: it represents the highest power output the laser will achieve, even if G-code commands request 100% power. All S-values in G-code are scaled to this maximum.

Example: setting `0.8` means S100% produces 80% actual laser power. Useful for preventing damage to both materials and the laser tube/diode.

WARNING: Does not provide emergency shutoff — use a kill switch for safety.

Sets the minimum PWM duty cycle (baseline power) for the laser, as a value from `0` to `1`. Used for travel moves to keep the laser active without actually burning, and as a floor for all laser operations. Also known as "tickle power" or "keepalive power".

Useful for some diode setups: keeps laser diodes thermally stable by preventing complete shutoff and reduces thermal stress from constant on/off cycling. During cutting operations, actual power is scaled between this minimum and the maximum power setting.

WARNING: Non-zero values mean the laser is always slightly active when the module is enabled.

DEPRECATED: Replaced by . It originally set a small baseline amount of power to keep the laser "tickled" (slightly active) during travel moves.

If you have old configuration files using this parameter, it will still work, since it provides the fallback default value for — but migrate to using instead for clarity and future compatibility.

Maximum S-value accepted from G-code commands. Determines the S-value range:

  • `1.0`: S0.0-S1.0 range (standard)
  • `100.0`: S0-S100 range
  • `255.0`: S0-S255 range (common in laser software)

The S-value is scaled to the 0-1 range internally based on this maximum. Does not affect actual laser power output, only G-code interpretation — this allows using G-code from different CAM packages without modification. Example: with `maximum_s_value=100`, S50 means 50% power.

Whether laser power should be proportional to the current speed: as movement speed ramps up (and down), laser power is proportionally adjusted so that the amount of laser power/quantity of photons for a given distance/area stays constant, even as speed increases or decreases progressively. This is true by default.

Enables automatic power scaling based on actual instantaneous movement speed. When enabled (default): `actual_power = requested_power × (current_speed / nominal_speed)`.

This:

  • Ensures uniform engraving depth and cutting quality despite speed variations
  • Compensates for machine acceleration and deceleration automatically
  • Prevents over-burning in corners where the machine slows down

Can also be controlled at runtime via M221 P command. WARNING: Disabling may cause uneven cuts/engraving due to speed variations.

PWM frequency expressed as the period in microseconds — sets the PWM period (and thus frequency) for laser control. The PWM frequency equals 1,000,000 divided by this period value.

This frequency affects how smoothly laser power can be controlled and must be appropriate for your specific laser driver electronics; the system uses this period to limit the maximum rate of power adjustments. Default is `20` microseconds.

Default S value for laser operations when no S parameter is specified in G-code, as a fraction from `0.0` (off) to `1.0` (full power). Used when G-code commands like M3 or M4 don't include an S parameter, and also serves as the initial power level before any S commands are received.

Typical laser default is `0.8` (80% power). Set lower for testing, higher for production.
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