Prusa link sd card emulation

Sarah_B · March 26, 2025, 3:44pm

hi,
I want to write a plugin to mimic sd card functions for prusa printers via prusaLink. The prusaLink part isn't hard.
I already have code to catch e.g. M20 (via queuing hook). What's missing for my first results is how to put my results in the received queue.

Any idea how to do that?

I saw this Handle M20 - List SD Card for printers don't support M20 but it misses some details for me, so I open a new thread...

thx in advance!

jneilliii · March 26, 2025, 10:02pm

For me and the Bambu plugin I'm able to do it through the serial factory I've added to the plugin to handle all serial communication back and forth. If you're not doing it all and just intercepting the M20 command you would have to call the internal comm layer received command I suspect. Something that uses the comm_instance parameter of the gcode queing callback, which is an instance of the MachineCom class. Seems like it might be difficult to do.

The other option, which I don't know if Prusa supports, is the use of M118 command, which basically tells the printer to send me back this line. So your hook captures queuing, grabs the file list, and then expands the command being sent to include a bunch of M118 commands with the file data lines appended.

Sarah_B · March 26, 2025, 10:28pm

M118 seams to work. nice idea! I want to replace the other not/not well supported SD commands.

I see I can control octoprint with that: "M118 A1 action:cancel" fancy
I looked already in the comm module and also find it hard to use for my purpose.

thx

jneilliii · March 27, 2025, 3:35am

Cool, so yeah that should work. In your gcode queueing hook, instead of returning line, you would return a list of M118 commands. Simple example (untested)...

def prusa_list(self, comm_instance, phase, cmd, cmd_type, gcode, subcode=None, tags=None *args, **kwargs):
    if gcode != "M20":
        return
    
    # code to get list of files and generate return data, ie dosname, date, size, unix timestamp, long filename
    file_list_commands = ["Begin file list"]

    for file in files:
        # dosname size timestamp "filename"
        file_list_commands .append(f"M118 {dosname } {size} {timestamp} \"{filename}\"") 

    file_list_commands.append("End file list")

    return file_list_commands

__plugin_hooks__ = {
    "octoprint.comm.protocol.gcode.queuing": prusa_list
}

you may also have to use the received phase gcode hook to manipulate how the printer sends the information (ie, remove "echo: " from the string possibly)

Sarah_B · March 27, 2025, 5:13am

Exactly what I did. Currently working on getting the M20 L to work for more then msdos filenames.

besides of the gcode commands I have the problem that file manager don't show my file list. I think I have to manipulate the printer capabilities.

jneilliii · March 27, 2025, 6:57pm

Yeah, I enabled long file name support and long file name writing, since I also am using the sd card upload hook.

github.com

jneilliii/OctoPrint-BambuPrinter/blob/d0fd4a5434043670c3fc02a2ce7020fc885be1d5/octoprint_bambu_printer/printer/bambu_virtual_printer.py#L442-L443


      
          self.sendIO("Cap:EXTENDED_M20:1")
          self.sendIO("Cap:LFN_WRITE:1")

jneilliii · March 27, 2025, 7:01pm

Oh more pointers on the dosname and timestamp. For timestamp I'm using OctoPrint's conversion from unix timestamp.

github.com

jneilliii/OctoPrint-BambuPrinter/blob/d0fd4a5434043670c3fc02a2ce7020fc885be1d5/octoprint_bambu_printer/printer/file_system/file_info.py#L7


      
          from __future__ import annotations

          

          from dataclasses import asdict, dataclass

          from datetime import datetime

          from pathlib import Path

          

          from octoprint.util.files import unix_timestamp_to_m20_timestamp

          

          

          @dataclass(frozen=True)

          class FileInfo:

              dosname: str

              path: Path

              size: int

              date: datetime

          

              @property

and for dosname I'm using OctoPrint's get_dos_filename

github.com

jneilliii/OctoPrint-BambuPrinter/blob/d0fd4a5434043670c3fc02a2ce7020fc885be1d5/octoprint_bambu_printer/printer/file_system/remote_sd_card_file_list.py#L8


      
          from __future__ import annotations
          
          import datetime
          from pathlib import Path
          from typing import Iterable, Iterator
          import logging.handlers
          
          from octoprint.util import get_dos_filename
          
          from .ftps_client import IoTFTPSClient, IoTFTPSConnection
          from .file_info import FileInfo
          
          
          class RemoteSDCardFileList:
          
              def __init__(self, settings) -> None:
                  self._settings = settings
                  self._selected_project_file: FileInfo | None = None

erffrfez · April 1, 2025, 4:05am

a meta-comment just to say "thanks". I'm not in this topic, but want to say in general that the world is a better place because of folks who help each other. I think you know that, and I don't think you are doing this just so that you get these "thanks", But it is important, so : kudos....
That is all

Sarah_B · April 1, 2025, 7:40am

Hi, @jneilliii thx for the answer. Main difference as I understand is that you have a complete printer plugin and I only a plugin that tries to modify the standard printer behaviour throug hooks and tricks.
This is my first plugin in octoprint and I'm feeling not ready for making a complete new printer class, albeit it might be better in the end.

My plugin shows files on sd card with long filenames and times (currently not the size of a file). I can load the file (with no analyze of the file) and delete a file. Also sd upload is possible.
I wasn't able to set capabilities, because i can't hook in the capability readout (with complete printer plugin as yours this is easy).

Currently I work on starting the print from sd card.
Any clue how I can hook in the analyze stuff so I can provide more informations of the file?

jneilliii · April 1, 2025, 12:30pm

Unfortunately analysis doesn't work on SD card files, I have the same problem with full virtual printer.

Sarah_B · April 1, 2025, 12:44pm

my plan is to have a custom GcodeAnalysisQueue that download the file and analyse it.

I look in plugin "prusa mini eta" there is a good example.