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Wes
 Wes
(@wes-4)
Trusted Member
telnet to printer?

I'm on the search for a minimal way to remotely start and stop SD card prints from my MK3S+MMU2S.  Octoprint has not been bug-free for me.

 

One approach I'm considering is simply telnet-ing to the serial interface of the printer (over the usb cable) from a local server box, and the starting or stopping SD card prints through telnet.  I'm assuming I could just use the commands here: https://prusa3d.github.io/Prusa-Firmware-Doc/group__GCodes.html

I would monitor the printer (and the lcd screen) via webcam.

I would disable the serial-connection reset feature as described here:

https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-user-mods-octoprint-enclosures-nozzles-.../octoprint-reseting-printer-power-panics/#post-154962

 

That way I could telnet in to start a print and immediately kill the session, and the telnet in again if I want to pause or stop.

 

Has anyone tried this?

(I have a flashair card for remotely sending files to the printer.)

Posted : 13/02/2020 12:12 am
vintagepc
(@vintagepc)
Member
RE: telnet to printer?

There are things you cannot interrupt or interact with via serial, many pause/alert screens for example. All you will get over serial is "busy processing". It will not accept commands in that state, you have to physically push a button.

Posted : 13/02/2020 3:26 am
Wes
 Wes
(@wes-4)
Trusted Member
Topic starter answered:
RE: telnet to printer?

Yes this would not be as good as actually having remote access to the input knob.  But in principle it is as powerful as Octoprint, right?

In any case, my goal is to do much less than octoprint, in exchange for avoiding the risk of octoprint messing up prints.

Posted : 13/02/2020 3:41 am
towlerg
(@towlerg)
Noble Member
RE: telnet to printer?

@wpegden

Although I havent got my printer yet, I've played with Octoprint running on an old PC and I pretty sure that statement is incorrect. If nothing else info is displayed on a much more usable format. A flexible plugin structure allow a myriad range of additional (and user tailorable) functions, anything from enclosure control to filament management to cancel one of many print objects.

It may be the case that some obscure function may only be available from the Prusa controller, you'd need to post the question on the Octoprint board.

Strongly suggest you try posting any problems you have experienced to the Octoprint board.

Posted : 13/02/2020 1:09 pm
towlerg
(@towlerg)
Noble Member
RE: telnet to printer?

@wpegden I tried to delete my previous post because on reflection I see you just don't want to run Octoprint. How about Pronterface or similar?

Posted : 13/02/2020 1:26 pm
vintagepc
(@vintagepc)
Member
RE: telnet to printer?
Posted by: @towlerg

@wpegden I tried to delete my previous post because on reflection I see you just don't want to run Octoprint. How about Pronterface or similar?

I would not suggest pronterface. It does not respect the "busy" commands from the printer and will continue to spam temp requests (M105). This can corrupt the buffer and insert M1s instead (esp. during MBL), making your printer seem to pause for no reason.

Posted : 13/02/2020 2:23 pm
Nikolai
(@nikolai)
Noble Member
RE: telnet to printer?

@wpegden

I think it's easier to run a stable Octoprint instead of reinventing the wheel on the shell level.
But sure, you can use any serial communication capable program. Or even write a simple python script for that. The critical part with connection resets is solved (and you've found this information already).

Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram

Posted : 13/02/2020 7:22 pm
Wes
 Wes
(@wes-4)
Trusted Member
Topic starter answered:
RE: telnet to printer?

@nikolai-r

I've gone back to octoprint several times but in the end it always ends with Octoprint stopping a print that was many hours in and me getting frustrated.

For example, there is currently a bug where SD card prints can get cancelled by octoprint:

https://github.com/foosel/OctoPrint/issues/3444

Which is what I think happened to me most recently, though I'm not sure.

 

I've also had the blue screen of death:

https://github.com/prusa3d/Prusa-Firmware/issues/2343

In general I think it's fair to say that octoprint is getting big and complicated fast enough that bugs happen with some frequency, including bugs that destroy prints.

Currently I have a long print going (sd only, no monitoring) but when it finishes I'm going to try to use gnu screen to connect to the printer and do basic things like start SD prints.

Posted : 14/02/2020 12:29 am
Nikolai
(@nikolai)
Noble Member
RE: telnet to printer?
Posted by: @wpegden

https://github.com/foosel/OctoPrint/issues/3444

Which is what I think happened to me most recently, though I'm not sure.

This one is easy to avoid by pausing only through Octoprint.

The other one is tricky as the root cause is unclear. Maybe it's being caused by a voltage spike in the serial connection. Something you might encounter again with any software. I've seen many weird stuff by static discharges. 

Anyway. Please report back with your simple solution. And describe in detail how it works. I'm pretty sure there are some people out there looking for alternatives.

Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram

Posted : 14/02/2020 12:50 am
towlerg
(@towlerg)
Noble Member
RE: telnet to printer?

FWIW Octoprint and an SD card really don't play well with each other. If you allow Octoprint to steam data it will be much more responsive to cancel/pause etc.

Posted : 09/02/2021 12:12 pm
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