# Recovering print after power shutdown **URL:** \ **Category:** General Discussion\ **Created:** [July 11, 2022, 2:35pm UTC](https://klipper.discourse.group/t/recovering-print-after-power-shutdown/3422 "2022-07-11T14:35:32Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![awitc](https://avatars.discourse-cdn.com/v4/letter/a/c77e96/32.png) [@awitc](https://klipper.discourse.group/u/awitc)\ **Post date:** [July 11, 2022, 2:35pm UTC](https://klipper.discourse.group/t/recovering-print-after-power-shutdown/3422/1 "2022-07-11T14:35:32Z")
Hello, I am in dire need of a solution for the print recovery problem. I have been browsing every available source of information regarding this and similar topics, like: > [@Resume Print after power loss](https://klipper.discourse.group/t/resume-print-after-power-loss/2682): > > After a power loss when the printer comes online how can the print be resumed? Is there any way of implementing this? Marlin 2.x has such a functionality if I recall. Thx > > > Hi, I am working on an implementation of power-off recovery and wanted to everyo…ne to be aware of it/review my implementation design. > > This implementation would depend on a power panic board, much like the Original Prusa i3 Mk3. It would add a new config option for specifying the power panic pin. > > Additionally, this assumes the power supply would provide around a second of operation after wall power is lost. Alternatively, the Raspberry Pi and MCU could be powered off of a 5v battery or some form of capacitor setup to substitute. > > Here is how it would work: > \- power panic signal is received from the power panic board > \- the MCU would decelerate the printer to a stop and record the remaining steps in the current move > \- the MCU would send an emergency signal to the Raspberry Pi containing the current x, y, and z axis position, and move queue > \- the Raspberry Pi would save this move queue, z axis info, set temperatures of the bed + extruders, and the filename of the current print to a file named resume.klipper or something > \- the Raspberry Pi then executes a shutdown command to safely turn off > \- upon boot Klipper checks to see if a resume file is present. If so, it heats the bed and extruder(s) up to the specified temperatures > \- Klipper sets the current z axis position to the one recorded in the resume file and then homes the x and y axis of the printer > \- Next Klipper loads the file using the Virtual SDCard feature. It looks for the first G1 command containing the current Z axis position as recorded in the resume file. > \- Klipper calculates the move queue as usual, but does not send it. Instead it goes through the file looking for a move queue that matches the one sent over by the MCU previously. > \- Klipper then moves the extruder to the recorded x and y position from the resume file > \- Klipper then sends over the move queue from the resume file and continues normally to the next set of moves > \- Klipper then deletes the resume file and continues on with the print as normal. > > If you have any concerns or advice regarding this implementation please let me know. I have looked through the code a lot and read the documentation and will be fully implementing this and sending a pull request soon. > > Thanks! > Cole > > \[klippy.log\](https://github.com/KevinOConnor/klipper/files/3189699/klippy.log) However, it seems that this is a very niche application and there is no working example, as there are many issues with the implementation. I have the BTT UPS module, which allows for the printer to be able to operate for several seconds after a power loss and can provide a signal, when the power is out. Additionally, for my particular application, I do not use a heated bed (which would eliminate adhesion issues, as there would be no need to reheat it). Hence I figure that it would be possible to make a save of the current print state whenever the power\_out pin is active and toggle a resume print window when the printer is able to run again. My main issue is the lack of proper understanding of inner workings of Klipper. I would greatly appreciate any feedback on how to implement any of the steps required to reach my goal. What I have in mind: Power is gone → Trigger UPS pin → Save position → Raise nozzle, shut-down printer Power is back → Resume? → Reheat nozzle → Read last coordinates → Continue the print I am familiar to python, but I am in no way close to understanding all of the Klipper code. If I could obtain any suggestions on how to proceed, I would be very thankful; i.e. which Klipper files are crucial for this functionality, where to add the file creation, etc. ---
**Author:** ![EddyMI3D](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/eddymi3d/32/1981_2.png) [@EddyMI3D](https://klipper.discourse.group/u/EddyMI3D)\ **Post date:** [September 10, 2024, 1:39pm UTC](https://klipper.discourse.group/t/recovering-print-after-power-shutdown/3422/2 "2024-09-10T13:39:03Z")