2 out of 10 Prusa printers won't connect to OctoPrint via serial port

[valentt]

Hello,

I have currently 10 Prusa printers (and growing) in my 3D printing farm, 7 are MK3 and 3 are MK3S.

One Prusa MK3 and one Prusa MK3S just won't connect to Raspberry Pi over serial port. I use same Raspberry Pi and same usb cable to connect to other 8 printer without problems.

Also boards and serial port on both "problematic" Prusa machines works ok when I connect to a laptop. I tried updating firmware to both "problematic" printers via two different laptops, one running Linux and other Windows, and this works without problem.

I can't figure out why these two have problems connecting to Raspberry Pi over serial, any ideas?

Does Prusa have different usb to serial chips on different boards? What could cause this?

Thanks!

[valentt]

A few minutes later I found this post:

OctoPrint won't connect to my Prusa MK3

If you are trying to connect to your MK3 or MK3s via a USB connection and it fails, make sure you have "RPi Port" set to "off" in the settings on your Prusa. ["RPi port" setting in the printer's settings] Other than the naming in the printer's settings might indicate "on" will simply make the USB port not work in favor of the GPIO pins on the Einsy. The mistake is hard to diagnose on first glance since there will be no error message generated by the printer, it will appear as a port to connect…

Changed RPI Port to off on first printer and now it connects, will try on second one as soon as it finishes current print job.

[Ewald_Ikemann]

@valentt

I use same Raspberry Pi and same usb cable

Just to clarify: In German language we differ two states of same:

1. "das Selbe" - that means this one item.
2. "das Gleiche" - an 100% identical 2nd item.

So you have troubles to connect with the same equipment as stated in 1. or in 2.?

[valentt]

@Ewald_Ikemann

das Selbe"

But if you see my second post the issue is resolved.

[Ewald_Ikemann]

I just saw your 2nd post when I hit the send button...