Prusa i3 MK3S+ with MMU2S Support
In reading through all the guides on this, there is a statement that says this only works on an i3 without a MMU. Is there a timeline for when the MMU will be supported through PrusaConnect? I would love to try this with my Prusa, but I don't want to remove the MMU components to use this setup.
What's the issue with MMU2S?
I am not saying that you should just go ahead, but I would like some developer to explain what is the matter with Prusa Link and MMU2S. I fail to see the issues but I am sure they are there.
From my limited view as a beta user of Prusa Link it just looks as a replacement of the SD-card printing for USB-printing. However, as I am not well versed in the inner working of MMU2S, I do not know if there is a hardware issue (like a busy serial port).
But if anyone knows, please share the info.
MMU2S
I just assume that this works. You might not get a nice interface for it yet, but as it was said it basically streams commands over UART/USB as-is.
In reading through all the guides on this, there is a statement that says this only works on an i3 without a MMU. Is there a timeline for when the MMU will be supported through PrusaConnect? I would love to try this with my Prusa, but I don't want to remove the MMU components to use this setup.
MMU2S
I do have an MMU connected and use it, but. I've been getting weird problems with wrong filaments getting selected and such. I do not think it is related, but I have removed the Zero for now to see if these things still happen now and then.
Serial port cannot be shared
I did some digging and it seems MMU2S uses EXT3 socket on the Einsy board where serial ports are exposed. Most likely they use for the MMU2S the same serial port Prusa Link uses to communicate the Raspberry with the Einsy too, thus raising the above-mentioned incompatibility.
Serial port / USB
@misan: Good finding! But then it should be possible to connect a Raspberry Pi via USB to the Einsy board to avoid the problem.
RE: Most likely but ...
The Pi Zero W should then avoid using the serial pins when/if connected to the Einsy board (which still can deliver the +5 power though). And an external cable could be needed to connect to the USB port (it might get ugly mechanically). Plus a config change is needed to point to the new port used.
Please note I am not a Prusa developer, so take my opinions with some caution. Hopefully someone from PR will chime in and set the record straight if needed.
Unsure of that
According to this: https://github.com/ultimachine/Einsy-Rambo/blob/1.1a/board/Project%20Outputs/Schematic%20Prints_Einsy%20Rambo_1.1a.PDF
The J19 that RPI0W uses exposes TX1/RX1. Where-as the P3 connector used by MMU2S uses upper row, which exposes TX2/RX2. This indicates to be two separate UART interfaces.
Version number
Please have a look at version 1.1b, which I think is the one used by MK3. (Maybe the result is the same though).
1.1b
I did not find schematic for 1.1b, but I would be surprised to be different for a build revision change.
MMU2S
MMU2S according to Prusa-FW uses UART2: https://github.com/prusa3d/Prusa-Firmware/blob/MK3/Firmware/uart2.c#L11
The RPI0W uses UART1: https://github.com/prusa3d/Prusa-Firmware/blob/MK3/Firmware/MarlinSerial.h#L121
The atmega32u8 exposed over USB uses UART0: https://github.com/prusa3d/Prusa-Firmware/blob/MK3/Firmware/MarlinSerial.h#L116
All of that is aligned with schematic.
More info
I have asked around and no, there is no incompatibility and some users are actually using MMU2S with Prusa Connect (thanks for the tip, Bart).
What I guess happens here is that MMU2S is not yet supported over Prusa Connect (you can print with it but there is no specific UI built). So @k3213 was absolutely right there is no hardware incompatibility (and I was wrong assuming it might be).
Not that @Peter-crepeau said it was incompatible though.
This is what I am using as my basis for this.
In reading the quick start guide, I took the following as MMU2S is not supported.
"The MMU2S upgrade functions aren't supported yet."
I'm not sure if that means that its not supported, or if it means that you cannot interact with the MMU2S via Prusa Link/Connect directly. I guess I'm really looking for clarity from PR as to what the above statement means.
RE: Prusa i3 MK3S+ with MMU2S Support
uz by se mohl pomalu nekdo z PR vyjadrit, jestli se pocita s podporou MMU2?
RE: Prusa i3 MK3S+ with MMU2S Support
For what its worth, I just setup my Prusa Link, and I have an MMU2S, and it's working perfectly. I didn't even look for any functionality in the UI for it, since my understanding of it is the same, no UI functionality for it. I just sent my first print via PrusaLink, and its a SINGLE color in MMU mode. And it worked as expected (did not prompt me to select a filament like it would in single mode) and used the proper filament.
I will test next with a true MMU print, but I see no real issues so far other than the obvious lack of MMU UI (things like "select filament 2" or whatever). Will update when after I run a true MMU print.
RE: Prusa i3 MK3S+ with MMU2S Support
On a MK3s+ with MMU2S a simple MMU test print with two colors was successfull. Prusa Link installed on a Raspberry 3b with ethernet connection. I does not see any difference in behaviour compared to octoprint.
RE: Prusa i3 MK3S+ with MMU2S Support
So far there is nothing in the UI to control the MMU which means if you use SINGLE mode you don't have any way to remotely choose which filament to load for the print.
Other than that for me using MMU in single mode works mostly fine* and multi mode is completely broken. *Still have to select filament at the start of the print manually on the he printer.
RE: Prusa i3 MK3S+ with MMU2S Support
I setup prusalink on my third mk3s+ (first Mmu2s) yesterday, and ran into an issue with the machine requesting attention on prusalink, display showing Mmu load failure, however, the mmu showed green led for the channel, and pressing the middle button resulted in zero errors. Pressing the right button made it switch filament to the next one over, as if the Mmu didn't know a print was running. I have made this print multiple times prior to the prusalink addition so I will disable it for now.
RE: Prusa i3 MK3S+ with MMU2S Support
I have been using PrusaLink during the summer on my MK3+MMU2S and have noticed some problems, but the problems seems to be random.
The problem that I get most, is that after a print, when the filament has unloaded, the printer wants me to change filament (the print head moves to the front right, like there has been a filament error, or you do a filement change without the MMU), and tell me to remove the filament (which is already unloaded) and then press the button.
When I press the button, it loads the filament and then parks the print head where the print stopped.
This behaviour I get often, but not every time.
Another error I have had, is that it selects the wrong filament, as if the printer and MMU is out of sync.
RE: Prusa i3 MK3S+ with MMU2S Support
Hi, sadly, I have not gotten around to the MMU just yet, Thank you for all the feedback tho, it is appreciated. I am now mostly focused on cameras. The mmu with potentially a big refactor (not fast) should be the next target