output synchronised to movement

I am using Repetier for a plotter.
I have now an inkjet head with 8 jets, each controlled by an output.
According to the distance I want to controll these jets.
eg. to write an "E": would be 1mm all 8 jets - then 3mm jet 1,5,8 - then no jet - then .. next letter

How can I synchronise the movement with the letters?
(speed is very low)
do we have a kind of interrupt of each mm?

Thanks for any help!


  • by thinking about it, I have atleast a first solution:
    1) I change in Repetier the E Appendix in the G0 command to controll the 8 jets
       (eg 255 for 8 outputs ON for the 8 jets)
    2) I write in VisualBasic a GC-Code Generator generating the E-Appendix of G0
    The code for the above example to make the letter "E" would be:
    G0 X1 E255 - go 1mm with all 8 jets to ON to make the first vertical line of the E
    G0 X4 E145 - go 3mm with jet 1,5,8 to On to make the 3 arms of the E
    G0 X1 E0 - go 1mm and no jets
    The code will tricky for letters with diagonal lines like "N"..then the steps must be smaller maybe 0.5mm.

    I assume that setting the outputs is fast enough.
    Or will stop the motion between the G0 commands?
    Make that sense?
  • No motion will optimize between moves, so that part would be ok. The problem is that motion takes place in a stepper interrupt and there informations like positions and E are lost. There is a field secondSpeed that controls laser intensity in laser mode that is set. You could modify the laser routines to use intensity as inkjet pattern and set it between G moves.
  • thanks for your input - then I make it with the Laser command, like
    G0 X1
    M5 S255
    G0 X4
    M5 S145
    G0 X5
    M5 S0

  • Don't forget to enable "laser" in that case! G0 is then without laser (travel) G1 is with laser.
  • thanks for the hint!
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