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.