Expected MMU2s behaviour for single mode spool join
With filament loaded in 1 (almost empty spool) and 2, I started a print by
- powering on printer
- telling Octoprint to connect, which it did
- selected the file to print in Octoprint
- the printer started printing with #1 without asking which filament to use, the display showed F?
- when 1 ran out, I was standing in front of it, the MMU detected the out-of-filament and right away the printer reset itself and that was it.
I unscrewed one of the pneumatic thingy to remove the small piece of filament left from #1, restarted the print from octoprint, and this time the printer asked which filament to use. I selected #2, the MMU homed, loaded #2, and it's printing now.
What went wrong that it didn't ask which filament to use on the first try?
RE: Expected MMU2s behaviour for single mode spool join
I've run into some odd things like this before. When it happens, I restart Octoprint, reslice the model, cycle printer power and reset the MMU. Usually one or two of those fixes the problem. Sometimes it requires all.
One I've seen more than once is when using single mode, it will load that filament 2-5, complete the priming strip, stop and then load filament 1. Nothing in the gcode telling it to load that number. No reason I can tell why it would want to change. Seems like every once in a while though, the MMU just needs to be reset.
RE: Expected MMU2s behaviour for single mode spool join
I once read that Octoprint when connecting causes some kind of reset in the printer. I assume that this might temporarily disconnects the MMU - so by starting the print quickly after connecting Octoprint, the printer might get confused if there's a MMU or not - and e.g. starts to print without asking for the filament.
In a situation like this (filament 5 already loaded, octoprint connecting, quick start of print) I once also got a strange "loading filament 256" message. To avoid all of this I usually give the printer a bit of time at the start. E.g. pre-heating the nozzle should give all systems involved enough time to complete all initialization.
RE: Expected MMU2s behaviour for single mode spool join
I once read that Octoprint when connecting causes some kind of reset in the printer. I assume that this might temporarily disconnects the MMU - so by starting the print quickly after connecting Octoprint, the printer might get confused if there's a MMU or not - and e.g. starts to print without asking for the filament.
In a situation like this (filament 5 already loaded, octoprint connecting, quick start of print) I once also got a strange "loading filament 256" message. To avoid all of this I usually give the printer a bit of time at the start. E.g. pre-heating the nozzle should give all systems involved enough time to complete all initialization.
In my original post's example, Octoprint and the printer were initialized. What I came to find out was that the MMU wasn't full initialized even though the printer was. This is a bit annoying to learn the hard way, the printer's firmware should be able to detect the MMU as soon as it's powered on and hold it until the MMU is initialized. Right now, the printer powers up, initializes quickly while the MMU powers up and "slowly" initialize. When you look at the printer's settings you'll notice it doesn't detect the MMU right away. If you start a print job before it sees it, it will probably work but it'll get screwed up if filament change is involved.
Also, the behaviour you describe regarding Octoprint resetting the printer is accurate if you have the option in Octoprint to automatically reconnect after a reboot.