Wrong layer count shown - PRUSA i3 MK3S MMU2S

LCD displays shows the current layer at 3 for the start of the print at the first layer.


Repetier Server 0.94
Printing a single colour with the PRUSA multi-material mode.
Raspberry Pi3



  • Can happen depending on start gcode. For the server every extrusion on a different height then before is a new layer. We do not know the slicer layer counting and have own numbering.  And prusa has always this purge line in front so that can already cause layer count to increase for a single move.
  • I watched the start and that's exactly what it's doing. When it starts the purge, layer count is at 1. When it finished the purge line, the layer count was at 3.

    Upon further checking, the purge line starts the purge at .40, then goes to .30 and finally ends the purge at .20 layer height. So that's where the server is picking up the three layers from.

    Makes the "printing X/500 layer" LCD display pointless because it's not accurate.

    Maybe a checkbox in a future version that asks if the printer does a prime line and subtracts "x" layers at the onset...:-)
  • A checkbox makes no sense. You would need to ask for every upload since it might also have no purge layer or one only at printing height. 
    Layer count is still useful to feel progress. There are also other cases with variable layer height that makes it impossible to see Z from layer count. But for that you also have Z position available.
  • I'm just reporting a bug. If it can't be fixed for whatever reason, just call it a bug that can't be fixed and leave it at that.

    But make a note in the documentation that it's a "feel" feature only on some printers.
  • YES, I also noticed this bug, I hope it gets fixed. Thanks.
  • It is not a bug! It is just another definition of layer. Other slicers have even negative layers for raft. So they differ all but we need a consistent system in server that works for all gcodes. Server definition of a layer is a new height where extrusion occurs. We anaylse the real motion and reduce these to layers. PrusaSlicer does not count height changes in start code so we can differ here since we analyse the file as it is. It matches the preview in 2d preview with it's layer preview.
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