What the Grbl audit checks
The parser recognizes the standard classic Grbl 1.1 settings: step pulse and idle timing; step, direction, homing, and report masks; Boolean switch, homing, limit, reporting, and laser options; junction and arc tolerances; homing rates and pull-off; spindle range; and X/Y/Z steps, maximum rate, acceleration, and travel. It checks numeric shape, Boolean and bit-mask ranges, duplicate settings, missing standard entries, soft-limit/homing dependency, spindle range order, and suspicious homing feed/seek order.
Reading masks and axis values
For $2, $3, and $23, bits 0, 1, and 2 represent X, Y, and Z. The report shows both the original number and decoded axes. Grbl 1.1 $10 uses two report bits: machine-versus-work position and optional planner/RX buffer data. $13=1 changes report display units, but the documented configuration values such as steps per millimetre, millimetres per minute, acceleration, and travel remain millimetre-based.
Using a baseline safely
Compare against a capture from the same controller, firmware family, machine, mechanics, drivers, and microstepping configuration. Settings are matched by exact number, including unknown fork-specific numbers. Added, removed, and numerically changed values stay distinct. A text difference is evidence to investigate—not proof that the current or baseline value is correct.
Machine-safety boundary
A structurally consistent settings dump is not a verified or safe CNC configuration. This page cannot identify wiring polarity, driver pulse requirements, steps, microstepping, leadscrew pitch, travel direction, switch behavior, usable envelope, motor limits, spindle range, laser interlocks, or safe acceleration. It never connects to hardware or sends commands. Back up the controller, consult the exact controller and machine documentation, change one value deliberately, read it back, and test at reduced energy with clearance and an accessible emergency stop.
Frequently asked questions
Can I paste a full serial-console capture?
Yes. Grbl greetings, ok, alarm/error responses, bracketed messages, and the typed $$ command are counted as ignored console lines. Unrecognized $number=value lines remain visible, while malformed setting lines are errors.
Does $13 convert the settings to inches?
No. It changes Grbl’s position-reporting display. The settings documented in millimetre-based units remain millimetre-based.
Why are unknown settings warnings instead of errors?
Grbl forks and vendor builds add settings. The tool preserves them for comparison and backup but refuses to invent their meaning or limits.
Can I send the normalized backup directly to my machine?
Do not treat it as an approved restore script. It is a sorted representation of parsed input. Review every value against a fresh read-back, the exact firmware, and the physical machine before making manual changes.
Primary references: the official Grbl repository’s Grbl v1.1 settings documentation and system-command documentation.
Audit a LinuxCNC tool table · Validate G2/G3 arc geometry · Browse machining tools