What M115 means
Marlin's response can include firmware name, version, source URL, protocol version, machine type, kinematics, extruder count and UUID. Builds with extended capability reporting can add feature flags. These are runtime controller claims and their exact fields depend on firmware and configuration.
Klipper documents M115 as a firmware-version request but recommends its API Server for external control. RepRapFirmware supports M115 with its own optional parameters and output. A slicer may place M115 in start code, yet a saved G-code file normally does not contain the live reply.
Syntax and parameters
M115No parametersRequests the target firmware's identification or capability report; response format is firmware-specific.
Practical examples
Request firmware information
M115A host sends this line to a connected controller. The request alone does not identify the firmware.
Keep request and response separate
M115 ; wait for the connected controller replyThe comment reminds a host workflow to wait for a live reply; it is not itself the reply or a timing guarantee.
Firmware context
| System | Status | What changes |
|---|---|---|
| Marlin | Common | Returns a structured human-readable identity line and may report extended capabilities when enabled. |
| Klipper | Common | Supported as a human-readable version request; the API Server is preferred for programmatic external control. |
| RepRapFirmware | Check dialect | Returns firmware version and capabilities with optional board/version-dependent parameters. |
| CNC controllers | Check dialect | Not a portable CNC identity command; use the controller's own interface and manual. |
What this viewer can show
The static viewer preserves the M115 line as source text but does not connect to a controller or fabricate a reply. It therefore cannot prove the printer's firmware, version, features or macro configuration.
Common mistakes
- Do not treat the presence of M115 as a firmware fingerprint.
- Capability fields are version- and build-dependent.
- A comment containing an old response may be stale and is still only file text.
Primary sources
This page is an original explanation, reviewed against the firmware documentation below. Always confirm commands against the firmware and configuration on the machine that will execute them.