G-code Dialect Support

Rayforge supports multiple G-code dialects to work with different controller firmware.

Supported Dialects

Rayforge currently supports these G-code dialects:

Dialect	Firmware	Common Use
Grbl (Compat)	GRBL 1.1+	Diode lasers, hobby CNC
Grbl (Compat, no Z axis)	GRBL 1.1+	2D laser cutters without Z
Grbl Raster	GRBL 1.1+	Optimized for raster work
GRBL Dynamic (Depth-Aware)	GRBL 1.1+	Depth-Aware laser engraving
GRBL Dynamic (no Z axis)	GRBL 1.1+	Depth-Aware laser engraving
LinuxCNC	LinuxCNC	Native Bézier (G5) support
Mach4 (M67 Analog)	Mach4	High-speed raster engraving
Smoothieware	Smoothieware	Laser cutters, CNC
Marlin	Marlin 2.0+	3D printers with laser

Recommended Dialects

Grbl (Compat) is the most tested and recommended dialect for standard laser applications.

Grbl Raster is optimized for raster engraving on GRBL controllers. It keeps the laser in dynamic power mode (M4) continuously and omits redundant feedrate commands, resulting in smoother and more compact G-code output.

GRBL Dynamic (Depth-Aware) is recommended for Depth-Aware laser engraving where power varies during cuts (e.g., variable depth engraving).

LinuxCNC supports native cubic Bézier curves through the G5 command, which produces very smooth and compact G-code for curved paths. When using this dialect, enable the "Support Bézier Curves" option in Advanced Machine Settings to take advantage of G5 output.

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Mach4 (M67 Analog)

The Mach4 (M67 Analog) dialect is designed for high-speed raster engraving with Mach4 controllers. It uses the M67 command with analog output for precise laser power control.

Key Features

• M67 Analog Output: Uses M67 E0 Q<0-255> for laser power instead of inline S commands
• Reduced Buffer Pressure: By separating power commands from motion commands, the controller buffer is less stressed during high-speed operations
• High-Speed Raster: Optimized for fast raster engraving operations

When to Use

Use this dialect when:

• You have a Mach4 controller with analog output capability
• You need high-speed raster engraving
• Your controller experiences buffer overflow with standard inline S commands

Command Format

The dialect generates G-code like:

M67 E0 Q127  ; Set laser power to 50% (127/255)
G1 X100 Y200 F1000  ; Move to position
M67 E0 Q0    ; Turn laser off

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Creating a Custom Dialect

To create a custom G-code dialect based on a built-in dialect:

1. Open Machine Settings → G-code Dialect
2. Click the Copy icon on a built-in dialect to create a new custom dialect
3. Edit the dialect settings as needed
4. Save your custom dialect

Each custom dialect is an independent copy. Changing one dialect never affects others, so you can freely experiment without worrying about breaking an existing setup. Custom dialects are stored in your configuration directory and can be shared.

Dialect Settings

When editing a custom dialect, the Settings page offers these options:

Continuous Laser Mode keeps the laser in dynamic power mode (M4) active throughout the entire job instead of toggling M4/M5 between segments. This is useful for raster engraving where the laser needs to stay on continuously during scan lines.

Modal Feedrate omits the feedrate parameter (F) from motion commands when it has not changed since the last command. This produces more compact G-code and reduces the amount of data sent to the controller.

Separate Laser-On Command for Focusing

Some dialects support configuring a separate command for turning the laser on at low power, which is useful for focus mode. This lets you use a different command for the visual "laser pointer" behavior than what is used during actual cutting or engraving. Check your dialect's settings page for this option.

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Template Placeholders

When creating or editing a custom dialect, each command template uses Python format string placeholders to inject dynamic values. Use {name} or {name:.0f} syntax (e.g., {power:.0f} to format as a decimal with no fractional digits).

Available Placeholders by Template

Template	Placeholders
Laser On	power
Focus Laser On	power
Laser Off	(none)
Tool Change	tool_number
Set Speed	speed
Travel Move	x, y, z, x_cmd, y_cmd, z_cmd, extra_cmd, f_command, s_command
Linear Move	x, y, z, x_cmd, y_cmd, z_cmd, extra_cmd, f_command, s_command, i, j, power
Arc (CW)	x, y, z, x_cmd, y_cmd, z_cmd, extra_cmd, f_command, s_command, i, j, power
Arc (CCW)	x, y, z, x_cmd, y_cmd, z_cmd, extra_cmd, f_command, s_command, i, j, power
Bezier Cubic	x, y, z, x_cmd, y_cmd, z_cmd, extra_cmd, f_command, s_command, i, j, p, q, power
Air On/Off	(none)
Home All	(none)
Home Axis	axis_letter
Move To	speed, x, y, z
Jog	speed
Clear Alarm	(none)
Set WCS Offset	p_num, x, y, z
Probe Cycle	axis_letter, max_travel, feed_rate
Dwell	seconds, milliseconds

Placeholder Reference

Coordinates

Placeholder	Description
x	Target X coordinate as a float (e.g., 100.0)
y	Target Y coordinate as a float (e.g., 200.0)
z	Target Z coordinate as a float (e.g., 5.0)
x_cmd	X-axis command string, e.g., " X100.0". Omitted when unchanged (if "Omit unchanged coordinates" is enabled)
y_cmd	Y-axis command string, e.g., " Y200.0". Omitted when unchanged
z_cmd	Z-axis command string, e.g., " Z5.0". Omitted when unchanged
extra_cmd	Extra axes command string for A, B, C axes (e.g., " A90.0"). Empty if no extra axes are configured

Motion

Placeholder	Description
f_command	Feedrate command string, e.g., " F3000". Omitted when modal and unchanged
s_command	Spindle/power command string, e.g., " S500". Used in dynamic/raster modes and continuous laser mode
i	Arc or Bézier control point X offset from start position
j	Arc or Bézier control point Y offset from start position
p	Second Bézier control point X offset from end position (Bezier Cubic only)
q	Second Bézier control point Y offset from end position (Bezier Cubic only)

Power and Speed

Placeholder	Description
power	Absolute laser power value (float). Supports format specifiers, e.g., {power:.0f} for no decimals
speed	Speed value (for Move To and Jog commands)
tool_number	Tool/laser head number

Machine and Probing

Placeholder	Description
axis_letter	Single axis letter, e.g., "X", "Y", "Z" (for Home Axis and Probe)
p_num	WCS P-number (e.g., 1 for G54)
max_travel	Maximum probe travel distance (Probe Cycle only)
feed_rate	Probe feedrate (Probe Cycle only)

Dwell

Placeholder	Description
seconds	Dwell duration in seconds as a float (e.g., 1.5)
milliseconds	Dwell duration in milliseconds as an integer (e.g., 1500)

Tips

• Format specifiers are supported: {power:.0f} formats power as an integer, {power:.2f} as two decimal places.
• The "Omit unchanged coordinates" setting controls whether x_cmd, y_cmd, and z_cmd are left empty when the axis position has not changed since the last command. This reduces G-code size.
• The "Modal Feedrate" setting controls whether f_command is omitted when the feedrate has not changed.
• Leave a template field empty to skip that command entirely (e.g., setting bezier_cubic to "" disables native Bézier output and falls back to linearization).

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Related Pages

• Exporting G-code - Export settings
• Firmware Compatibility - Firmware versions
• Device Settings - GRBL configuration
• Macros & Hooks - Custom G-code injection