Only one z probe before M3

I'm new here!!! First I want to apologize for my bad English!
I built a CNC plasma cutter. The machine is controlled with Ramps 1.4 and repetier firmware. Everything is fine. Now I want to control the z-axis in such a way that after the M3 S255 command (switch plasma relay on) the Z-axis first moves to the z-max limit switch and then back to a certain height. Only then is ignited. Is this possible?


  • Why not
    G28 Z0
    G0 Z20
    M3 S255

    As I understood M3 S255 is igniting for you so going first to position would be the logic consequence.
    If you want this all in M3 then it is not supported and you would have to edit the sources to do exactly that.
  • Thank you!
     I tried it and it works. My mistake was that the zero point of the Z axis was up. I changed that now in the firmware. I would like to try to execute these commands with M3. Can you give me a hint where in the firmware I can search there?Thanks a lot!
  • Hello
    I was able to solve the lifting problem (G0 Z5) with ENDSTOP_BACK_ON_HOME 5. Now it would be nice if M3 S255 could trigger the command G28 Z0.
    Where could I possibly set that?
    greetings from Liechtenstein
  • OK. I found it myself. In Commands.ccp on line 1624 I have inserted "Printer :: homeAxis (false, false, true);" . Now the M3 command does exactly what I want.
    Thank you anyway!
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