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@PavelSindler PavelSindler released this Apr 18, 2019 · 8 commits to MK2 since this release

This firmware for MK2/S contains important safety improvement in preheat error and also chosen features from MK3S branch.


  • Preheat error improved
  • Improved temperature regulation
  • Remaining time estimation
  • Adjustable beeper notifications
  • Incomplete file check updated
  • G-code fixes (M27, M110, M115)

Detailed description of changes:

Preheat error improved:

On older firmware version there was a zone where preheat error was not working properly. If thermistor would be damaged during the preheating phase in a particular way (resistance of damaged thermistor would be in the range corresponding to the measured temperature > 150 °C), preheat error was not triggered.
Improved preheat error now works in full range. MK2/S implementation also contains update which should prevent false bed preheat error occurrence.

Improved temperature regulation:

When changing temperatures during the print, temperature regulation was very slow in some cases. Regulation has been improved.

Remaining time estimation:

The current firmware version is ready to display remaining time estimation and accurate progress on printer status screen. Information about remaining time will be counted by Slic3r and inserted into G-code file. Gcode M73 is used for this. In this case, the letter 'R' is shown next to print time to indicate that it is remaining time estimation. For speed factor different than 100 %, time estimation may not be accurate, which is then indicated by the letter '?'. In case that there are no M73 G-codes in a file, printer behaves as in previous release versions, i.e. showing time from the print start. The status screen was slightly modified because of this feature. Symbol "SD" is now shown on printer status screen only during active SD print (i.e. not in idle state) together with progress in percentage. When printing over USB, there is a "USB" symbol shown together with progress in percentage.

It is possible to turn on/off estimated print time support in Slic3r by switching to expert mode and clicking on "Supports remaining time" check-box in Slic3r Printer Settings -> General. In future versions of Slic3r settings,

Adjustable beeper notifications:

In Prusa MK3S/MK2.5S firmware there are different levels of the acoustic signalization (since 3.4.0 firmware version). This feature has been ported to MK2/S firmware. User is able to choose between each level in the printer's menu -> Settings –> Sound. You can also change the sound settings during the print in the menu -> Tune.

Level description:
Loud - printer uses acoustic signalization for a failure or if confirmation is needed
Once - this level is similar to Loud, but all beeps are played only once.
Silent - most of the beeps are muted, the user is informed only in case of a serious error

Mute option (all beeps muted, used in MK3S/MK2.5S printers from 3.4.0 release) has been excluded for safety reasons.

Incomplete file check updated:

Last firmware 3.1.0 for MK2/S can falsely report that printed G-code file is incomplete. This was happening typically with G-code files generated in new Prusa Slic3r versions. This has been fixed.

G-code fixes:

G-codes which are used to report printer status (M27), machine type and firmware version (M115) and to set line number (M110) when printing remotely (for example using Octoprint) have been fixed.


  • Translation correction
  • Stop print fix
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