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Specification version v0.1

bambu

tested on simulator

Tier Tier 3
Protocol Bambu Lab LAN MQTT over TLS, Developer Mode
Covers Bambu Lab X1 series, Bambu Lab P1 series, Bambu Lab A1 and A1 mini
Hazard default medium
Conformance full
Tested with real paho-mqtt client over TLS against a simulated printer on an in-process broker

Estimated reach. About ten printer models. Bambu Lab sells the X1, P1, A1 and newer H2 and P2 families, which share one report format on the local MQTT broker. Bambu Lab documents Developer Mode for X1, P1, A1 and A1 mini, and only printers in that mode accept the commands this driver sends. Reads work in normal LAN mode too. Bambu Lab doesn't publish the message format, so the field list follows community documentation and may miss model-specific fields.

The bambu driver reads a Bambu Lab printer's status and pauses, resumes and stops prints through the printer's local MQTT broker, with paho-mqtt. The printer needs LAN-only mode and Developer Mode on.

Local access status

Checked 2026-10-24.

  • Since January 2025, Authorization Control firmware gates print starts, motion, temperature, fans, the AMS and calibration in cloud and normal LAN mode, from 01.08.03.00 on X1 and later on the P and A series. MQTT status stays readable.
  • Developer Mode, opt-in at the printer on X1, P1, A1 and A1 mini, leaves MQTT, the live stream and FTP open on the local network. Bambu Lab gives no support for the mode, and the owner secures the network. Reports of the mode on H2D and P2S are unchecked.
  • Section 3.1 of the Bambu Lab Terms of Use, quoted secondhand, restricts building software for Bambu Lab products without consent. In April 2026 Bambu Lab sent a cease-and-desist to an OrcaSlicer fork that reached Bambu Cloud posing as Bambu Studio. The owner reviewed this on 2026-10-25 and approved the driver.

The driver uses only the local MQTT interface and the LAN access code, never Bambu Cloud, Bambu Connect or an authorization bypass, and never poses as Bambu Studio. The driver sends only status requests and pause, resume, stop, speed level and chamber light commands. Without Developer Mode, commands fail with a hint and reads still work.

Setup

uv tool install --compile-bytecode "halkit[bambu] @ git+https://github.com/sohan-bhat/OpenHAL"
  1. On the printer, turn on LAN-only mode, then Developer Mode. Note the access code and serial number.
  2. export BAMBU_ACCESS_CODE=12345678 with your code.
  3. Put the certificate fingerprint in cert_sha256, as in step 2 of docs/hardware-tests/bambu.md.
ParameterDefaultMeaning
hostrequiredPrinter address. bambu: 192.168.1.50 is shorthand
serialrequiredSerial number, which names the MQTT topics
port8883MQTT over TLS
token_envBAMBU_ACCESS_CODEVariable holding the access code
cert_sha256noneQuoted SHA-256 certificate fingerprint, colons optional
ca_envnoneInstead of cert_sha256, a variable holding the path of Bambu Lab's CA certificate, checked with the serial
timeout5 sLogin, status and acknowledgement deadline
reply_wait2 sTime allowed for a command reply
safe_stopstopWhat a hub stop sends, stop or pause

The printer certificate names the serial and is signed by Bambu Lab's own CA, so ordinary TLS checks fail. The driver checks the pin before the access code leaves the hub.

Channels

ChannelReport fieldType and unit
stategcode_stateenum of idle, prepare, slicing, running, pause, finish, failed
nozzle_temp, nozzle_targetnozzle_temper, nozzle_target_temperdegC
bed_temp, bed_targetbed_temper, bed_target_temperdegC
chamber_tempchamber_temperdegC
progressmc_percentpercent
remainingmc_remaining_timemin
layer, total_layerslayer_num, total_layer_numdimensionless
jobsubtask_namestring
print_errorprint_errordimensionless
wifi_signalwifi_signalstring
speed_levelspd_lvlenum of silent, standard, sport, ludicrous, settable
chamber_lightlights_reportbool, settable

Other report fields read through a map such as map: { field: cooling_fan_speed, scale: 6.6667 }, with an optional unit. Actions pause, resume and stop take no arguments, and map: { command: pause } gives one another name. discover() listens for SSDP on UDP port 2021 and sends nothing. describe() suggests channels from the report.

Behavior

  • The driver requests one full report on connect and merges later reports, since P1 and A1 printers send only changes. Unsent fields read as no value. No polling.
  • Commands go out at QoS 1 and are never queued. A missing broker acknowledgement drops the connection, so no command arrives late.
  • A failure reply raises DriverError with the printer's reason, and some firmware sends no reply, so check state. Login and pin failures name what to check.

Example

openhal/drivers/bambu/examples/p1s-lan.hal.yaml reads a P1S and pauses, resumes and stops, with stop confirmed.

Limitations

  • By design, no print start, upload, camera, AMS, G-code, temperature targets or motion.
  • MQTT 3.1.1, one printer per file.
  • Untested on real printers. The simulator follows community documentation of the report format.

Hazard default and safe state

Medium. safe_state_support is native. A hub stop sends stop and the firmware ends the print, turns the heaters off and parks the head. A lost connection leaves the print running.

Sources

OpenHAL is an open protocol, released under Apache 2.0.

OpenHAL is not affiliated with Anthropic or MHS.

Source on GitHub

Specification v0.1