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Power Loss Resume Function in Klipper

Overview

  • The power loss resume function in Klipper refers to the ability to automatically restore the printing state of Klipper after it has been powered off and then powered on again.
  • This function requires the use of a safety shutdown module.
  • It is not applicable for machines where the Z-axis will move when the power is cut.

Configuration

Disable Power Off Shutdown

Note
  • You need to disable the power-off shutdown, otherwise the power loss resume function cannot be used.
  • The power loss resume function includes an automatic shutdown after saving progress.
  • Enter the device's IP address in the browser's address bar, for example: http://192.168.6.179

  • Access the configuration page

    • Open the device IP address in the browser, for example: http://192.168.1.2/
    • In fluidd, uncheck as shown in the left image -> Filter hidden files and folders.
    • In mainsail, check as shown in the right image -> Show hidden files.
    • At this point, you can see the .flyos-config folder. Inside this folder, there will be a sys-config.conf file.
    • The sys-config.conf file is a symbolic link to the config.txt configuration file in the removable disk FlyOS-Conf.
    • Open the sys-config.conf file and locate the configurations shutdown_pin_state and shutdown_pin=.
    • Add a # before these configurations.
    • Then save and close, and restart the system.

plr.cfg Configuration File

  • In the printer configuration page, find the plr.cfg file.

  • Empty the content inside, then paste the following configuration into it.

  • The content of the configuration file is as follows:

    [mcu host]   
    serial: /tmp/klipper_host_mcu

    [power_loss_resume]
    power_pin: !host:gpiochip0/gpio260 # Shutdown pin of the safety shutdown module, connected to PA21 pin on the host machine
    is_shutdown: True # Whether to execute shutdown operation, default is enabled
    paused_recover_z: -2.0 # Z movement distance during recovery if the machine is paused during shutdown, default is no movement
    start_gcode:
    # G-code to execute before resuming print
    # All parameters saved before power loss can be accessed via {PLR}
    # Use M118 {PLR} to output all available parameters
    M118 Starting resume: {PLR.print_stats.filename}
    M118 Interruption position: X:[{PLR.POS_X}] Y:[{PLR.POS_Y}] Z:[{PLR.POS_Z}] E:[{PLR.POS_E}]
    M140 S{PLR.bed.target} ; Set bed temperature
    M104 S{PLR.extruder.target-10} ; Set extruder temperature
    M109 S{PLR.extruder.target-10} ; Wait for extruder to heat up to set temperature
    G91 ; Relative coordinates
    G1 Z2 F100 ; Raise Z, prepare for X,Y homing
    G90 ; Absolute coordinates
    G28 X Y ; Home XY
    M140 S{PLR.bed.target} ; Set bed temperature
    M104 S{PLR.extruder.target} ; Set extruder temperature
    M190 S{PLR.bed.target} ; Wait for bed to heat up to set temperature
    M109 S{PLR.extruder.target} ; Wait for extruder to heat up to set temperature
    M83 ; Relative extrusion
    # G1 E0.5 F400 ; Extrude a bit
    layer_count: 2 # Execute layer_change_gcode after resuming specified number of layers
    layer_change_gcode:
    # G-code to execute after resuming {layer_count} layers
    M118 Resume print speed
    M106 S{PLR.fan_speed} ; Turn on part cooling fan
    M220 S{PLR.move_speed_percent} ; Set requested speed percentage
    M221 S{PLR.extrude_speed_percent} ; Set requested extrude speed percentage
    shutdown_gcode:
    # G-code to execute before shutdown
    M118 Low power voltage, shutting down
    # M112 ; Emergency stop

    Note
    • The start_gcode macro in the above configuration file may need modification based on the specific machine's actual situation.
  • After saving the configuration file,

  • Open the printer.cfg file and add the following content at the beginning of the file:


    [include plr.cfg]

  • Click the Save button in the top right corner and restart the system.

  • The power loss resume function in Klipper is now configured.

Testing

  • Start printing any file. During the print process, click the Emergency Stop button to simulate a power failure.
  • Click Firmware Restart, wait for Klipper to connect normally.
  • If a pop-up prompt appears on the webpage or KlipperScreen, it indicates that the power loss resume function is working properly.
  • You can continue testing with real power failure scenarios later.
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