Power Loss Resume Function in Klipper

Overview

• The Power Loss Resume Function in Klipper refers to the ability of Klipper to automatically restore the print status after power is restored following a power outage.
• This function can be used only when combined with the FAST system.
• PI-V2 requires the KPPM power loss module to be used.
• Not suitable for machines where the Z-axis may experience displacement after a power outage.
• Introduction to KPPM

Configuration

Disable Power Off Shutdown

Note

• To use power loss resume, you need to disable power off shutdown.
• The power loss resume has a function to automatically shut down after saving progress.
• Make sure no other power supply is connected to the host, otherwise it will not start up

• 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/
  • For fluidd, as shown on the left in the picture, uncheck -> Filter hidden files and folders.
  • For mainsail, as shown on the right in the picture, check -> Show hidden files.
  • 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 configuration file config.txt 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

Note

• Please replace the following in the configuration file: (PINS)
• with host:gpiochip1/gpio21

• In the printer configuration page, find the plr.cfg file.
• Clear its content, then paste the configuration below
• The configuration file content is as follows:

[mcu host]   
serial: /tmp/klipper_host_mcu

[power_loss_resume]
power_pin: (PINS)
is_shutdown: True # Whether to perform shutdown operation, default is enabled
paused_recover_z: -2.0 # If the print was paused when the power was lost, the Z movement distance when resuming, default is no movement
start_gcode:
    # Gcode to be executed before resuming
    # All parameters saved before power loss can be obtained through {PLR}
    # You can use M118 {PLR} to output all available parameters
    M118 Resuming print: {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 to set temperature
    G91                             ; Relative coordinates
    G1 Z2 F100                      ; Lift Z, prepare to zero X,Y
    G90                             ; Absolute coordinates
    G28 X Y                         ; Zero 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 to set temperature
    M109 S{PLR.extruder.target}     ; Wait for extruder to heat 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 be executed 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 be executed 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 Klipper power loss resume function has been configured.

Notes on [homing_override]

Note

• Note that if you use [homing_override], you cannot arbitrarily set the homing position in [homing_override]. If it causes failure of power loss resume, we are not responsible.
• Below there is a description of the [homing_override] configuration.

• 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 such, it may cause the power loss resume to fail.
  • The following [homing_override] configuration is to correctly home 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 only executes actions 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 appears on the web page or KlipperScreen, it indicates that the power loss resume function is working properly.
• Subsequent tests can be done with real power outages.