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Power Loss Resume Function for Klipper

Overview​

  • The power loss resume function for Klipper refers to the ability of Klipper to automatically recover its printing status after being powered off and then powered on again.
  • This feature requires the use of a safety shutdown module.
  • It is not suitable for models where the Z-axis will move when there is a power failure.

Configuration​

Configuration File plr.cfg​

  • In the printer configuration page, click "New Configuration" and create a plr.cfg file.

  • The content of the configuration file is as follows:

    [power_loss_resume]
    # power_pin: PA0 # Shutdown pin of the safety shutdown module, connected to PA0 on the lower machine
    power_pin: host:gpiochip1/gpio21 # Shutdown pin of the safety shutdown module, connected to PA21 on the upper machine
    is_shutdown: True # Whether to execute a shutdown operation, defaults to enabled
    start_gcode:
        # G-code to be executed before resuming printing
        # All parameters saved before the power failure can be accessed through {PLR}
        # Use M118 {PLR} to output all available parameters
        M118 Starting resume 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 the extruder to heat up to the set temperature
        G91                             ; Relative coordinates
        G1 Z2 F100                      ; Raise Z, prepare for X,Y zeroing
        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 the bed to heat up to the set temperature
        M109 S{PLR.extruder.target}     ; Wait for the extruder to heat up to the set temperature
        M83                             ; Relative extrusion
        # G1 E0.5 F400                  ; Extrude a bit
    layer_count: 2 # Resume printing after specified number of layers and execute layer_change_gcode
    layer_change_gcode:                
        # G-code to be executed after resuming {layer_count} layers
        M118 Resuming print speed
        M106 S{PLR.fan_speed}             ; Turn on the 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 be executed before shutdown
        M118 Low power supply voltage, shutting down
        # M112 ; Emergency stop

    Note
    • The macro in the start_gcode above may need to be modified according to the actual machine conditions.

  • Save 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" at the top right and restart.

  • At this point, the power loss resume function for Klipper has been configured.

Testing​

  • Print any file, and during the print process, click the "Emergency Stop" button to simulate a power failure.
  • Then 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 to test with real power failures later.