Definition

After power-up, stepper-based printers usually know how many steps they command but not where the carriage physically started. Homing moves toward a configured end, detects a switch or sensor, backs off as configured and assigns a reference coordinate.

Hardware endstops provide a signal; software endstops limit commanded coordinates after a reference exists. Neither guarantees that every later move was physically completed. Lost steps, a released motor or manual movement can make the controller's remembered position differ from reality until the axis is homed again.

What matters in practice

Reference before trust

Coordinates are only physically meaningful after the machine establishes a known frame.

Probe is not always endstop

A Z probe may home Z, measure a bed mesh, or do both depending on configuration.

Limits need position

Software endstops protect a numeric range but rely on the coordinate reference being correct.

Example in G-code

Home all axes, then report

G28
M114

The first command establishes the configured references; the second asks firmware to report its resulting logical position.

What this viewer can show

In this viewer

For printer-style G28, the viewer resets named axes in its analysis frame so later geometry remains coherent. It cannot simulate switches, probe clearance, sensor failure or a controller-specific homing macro.

Primary sources

This explanation uses firmware documentation and details visible in G-code. Your printer's settings still determine what the machine does.