Power Loss Resume Function of Klipper

Overview

The power loss resume function of Klipper refers to the ability to automatically restore the printing status of Klipper after it is powered off and then powered on again.
This function needs to be used in conjunction with the Safe Shutdown Module.
It is not applicable for models where the Z-axis will move when the power is cut.

Configuration

plr.cfg Configuration File

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

The content of the configuration file is as follows:

[power_loss_resume]
# power_pin: PA0 # The shutdown pin of the safe shutdown module connected to PA0 pin of the lower computer
power_pin: host:gpiochip1/gpio21 # The shutdown pin of the safe shutdown module connected to PA21 pin of the upper computer
is_shutdown: True # Whether to execute the shutdown operation, enabled by default
paused_recover_z: -2.0 # If the machine is paused during shutdown, the Z movement distance when resuming print, no movement by default
start_gcode:
    # G-code to be executed before resuming print
    # All parameters saved before power failure can be accessed via {PLR}
    # Available parameters can be output using M118 {PLR}
    M118 Start Resuming Print: {PLR.print_stats.filename}
    M118 Interrupt 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 reach set temperature
    G91                             ; Relative coordinates
    G1 Z2 F100                      ; Lift 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 reach set temperature
    M109 S{PLR.extruder.target}     ; Wait for extruder to reach set temperature
    M83                             ; Relative extrusion
    # G1 E0.5 F400                  ; Extrude a bit
layer_count: 2 # Resume printing specified number of layers and execute layer_change_gcode
layer_change_gcode:                
    # G-code to be executed after resuming {layer_count} layers
    M118 Resume Printing Speed
    M106 S{PLR.fan_speed}             ; Turn on the 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 Voltage, Shutdown
    # M112 ; Emergency stop

Note

The start_gcode macro in the above configuration file may need to be modified according to the actual machine situation.

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 the "Save" button on the top right and restart.
The power loss resume function of Klipper has been configured.

Testing

Print any file, and click the "Emergency Stop" button during the print process to simulate a power failure.
Click "Firmware Restart" again, wait for Klipper to connect normally.
If a pop-up prompt appears on the web page or KlipperScreen, it indicates that the power loss resume function is working properly.
You can continue to test the real power failure situation later.

Overview​

Configuration​

plr.cfg Configuration File​

Testing​

Overview

Configuration

plr.cfg Configuration File

Testing