Power Loss Resume Function in Klipper

• The Power Loss Resume function in Klipper refers to the ability to automatically restore the printing state of Klipper after it loses power and is powered again.
• C8P can be used without KPPM
• Not suitable for models where the Z-axis may shift after a power outage.

Configuration

Disable Power Off Shutdown

Notes

• Power Off Shutdown needs to be disabled, otherwise the Power Loss Resume function cannot be used.
• There is an automatic shutdown function after saving the progress in the Power Loss Resume.
• Please ensure that there is no other power connected to the host, otherwise it will not be able to start.

• Enter the device's IP address in the browser's address bar, for example: http://192.168.6.179

• Enter the configuration page

  • Open the device ip address in the browser, for example: http://192.168.1.2/
  • In fluidd, uncheck as shown on the left in the figure.
  • In mainsail, check as shown on the right in the figure.
  • At this point, you can see the .flyos-config folder, entering this folder will have the sys-config.conf file.
  • The sys-config.conf file is a soft link to the config.txt file in the removable disk FlyOS-Conf.
  
  • Open the sys-config.conf file, find the configurations shutdown_pin_state and shutdown_pin=
  • Add # before these configurations
  • Then Save -> Close and restart
  

plr.cfg Configuration File

Notes

• In the printer configuration page, find the plr.cfg file.
• Clear the content of it, then paste the following configuration into it
• The configuration file content is as follows:

[mcu host]   
serial: /tmp/klipper_host_mcu

[power_loss_resume]
power_pin: !host:gpiochip0/gpio260
is_shutdown: True # Whether to perform shutdown operation, default is enabled
paused_recover_z: -2.0 # Z movement distance when resuming print if stopped, default is no movement
start_gcode:
    # Gcode to execute before resuming print
    # All parameters saved before power loss can be obtained through {PLR}
    # Use M118 {PLR} to output all available parameters
    M118 Resuming print: {PLR.print_stats.filename}
    M118 Position at interruption: 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                      ; Lift Z, prepare to home X,Y
    G90                             ; Absolute coordinates
    G28 X Y                         ; Home X Y
    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 little
layer_count: 2 # Execute layer_change_gcode after resuming specified layers
layer_change_gcode:                
    # Gcode to execute after resuming {layer_count} layers
    M118 Resume print speed
    M106 S{PLR.fan_speed}             ; Turn on cooling fan
    M220 S{PLR.move_speed_percent}    ; Set requested speed percentage
    M221 S{PLR.extrude_speed_percent} ; Set requested extrusion speed percentage
shutdown_gcode:
    # Gcode to execute before shutdown
    M118 Low power voltage, shutdown
    # M112 ; Emergency stop

• After saving the above configuration file

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

  
  [include plr.cfg]
  

• Click Save and Restart in the top right corner.

• At this point, the Power Loss Resume function in Klipper has been configured.

Notes on [homing_override]

Notice

• Note that if you use [homing_override], you should not set the homing position arbitrarily in [homing_override]. The failure of the Power Loss Resume function caused by this will not be responsible.
• Below is the configuration description of [homing_override]

• Description
  • [force_move]: Enable the force move function, allowing to move to a specified position.
  • [force_move] replaces the set_position_z function in [homing_override]. If not configured as described, it may cause the Power Loss Resume function to fail.
  • The following [homing_override] configuration is to ensure correct homing of the Z-axis during Power Loss Resume.

[force_move]
enable_force_move: true


[homing_override]
axes: z
gcode:
    {% set max_x = printer.configfile.config["stepper_x"]["position_max"]|float %}
    {% set max_y = printer.configfile.config["stepper_y"]["position_max"]|float %}
    {% if 'z' not in printer.toolhead.homed_axes %}
        SET_KINEMATIC_POSITION Z=0
        G90
        G0 Z5 F600
    {% endif %}
    {% set home_all = 'X' not in params and 'Y' not in params and 'Z' not in params %}

    {% if home_all or 'X' in params %}
    G28 X
    {% endif %}

    {% if home_all or 'Y' in params %}
    G28 Y
    {% endif %}

    {% if home_all or 'Z' in params %}
    G0 X{max_x / 2} Y{max_y / 2}  F3600 
    G28 Z
    G1 Z10 F2000
    {% endif %}

• Notes on lifting
  • This configuration is executed only when the Z-axis is not homed, and this configuration does not affect normal use

  {% if 'z' not in printer.toolhead.homed_axes %}
      SET_KINEMATIC_POSITION Z=0
      G90
      G0 Z5 F600
  {% endif %}

Test

• Print any file, click the Emergency Stop button during printing to simulate a power outage.
• Click Firmware Restart again, wait for Klipper to connect normally.
• If a pop-up window appears on the web page or KlipperScreen, it indicates that the Power Loss Resume function is working properly.
• You can continue to test real power outages later.