Axis DRO's

The DRO's should always display the machines real coordinates. I understand that this can't always be the case as there is no easy way to really know where the machine is at any point in time. Offsets (G92) are not accurately displayed. However, if the user or GCode issues a M114 the response is the actual machine coordinates.

Would it be possible to update the DRO's with M114 values?




  • What is DRO?

    Because firmware buffers moves we never know what the current position is. We show the position of last move send knowing that after some time printer will be at that position.

    Then being idle and you send M114 the position is queried from firmware, in other cases as explained it gets ignored. We always add G92 offsets to show real coordinates.
  • The DRO's are the X Y Z position indicators on the screen.

    If the machine is idle and I send a M114 why can't theses position indicators be updated to the returned values. I am much more concerned about where the machine knows it is than Repetier thinks it is. 

    Simple case. Where I want to go is a negative coordinate on an axis. I do a goto axis 0 (G01 X0). I do a G92 X10 to reset the X axis machine position to zero. X DRO stays unchanged. If I jog X DRO shows a negative number which does not reflect the machine coordinate. I am not able to manually  enter a Gcode based on the X DRO that will move me to where I want to go. I have to do an M114 to get the actual coordinates and go from there.

    There is nothing magical about negative positions. They are a consequence of the coordinate system and Repetier should fully support them.

  • Unless you are in CNC mode in host, host will show real positions including G92 offsets. That is why G92 has no effect on shown coordinates.
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