M280 GCode out of order

Hi,

I'm currently building a pen plotter using Marlin firmware v1.1.3.
I'm using RC servo to lift the pen instead of stepper, so my Z axis control is M280 P0 Sxx instead of G1 Zxx
When I try to draw something the home axes command finished correctly, but during the first move the pen went up and down several times (creating a dashed lines) and didn't lift during the draw (just drawing in the air)
It looks like all of my M280 commands take precedence of my G0 and G1 commands.
I was looking into the source code (of the Marlin) but found any explanation for this.
If somebody has any idea, how to correct this please let me know.

Thanks,

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SUF
Electronics, 3D hobbyist
[pakahuszar.blogspot.com]

Some commands are marked as can do now...

Since a servo is not normally important (on a normal machine), yes its get executed while other moves are happening out or order

you need a M400: Wait for current moves to finish before each servo move command

Edited 1 time(s). Last edit at 08/20/2017 09:38PM by Dust.

Thank you,

It worked perfectly.