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Author Topic: Mach 3 lag between stopping a move and M9  (Read 822 times)

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Mach 3 lag between stopping a move and M9
« on: June 07, 2017, 09:46:48 AM »
Hello:
I have a hobby CNC 3 axis gantry using an Optimum BF20 drive, SmoothStepper Ethernet and Mach3.
Want to do TIG welding.
I have the welder set up and the GCode works.
I am using M7 to turn on the welder and M9 to turn it off.
There is a 5 VDC Relay attached to the welder to turn the welder on and off and isolate the welder from the Optimum box.
The problem is there is a very long lag time between an M7 command and the G01 and another long lag between the the gantry stopping movement and the M9 (Stop welder) command.
So long in fact I am blowing a hole at the end of the weld.
I have tried everything I can think of but no matter what the welder takes too long to shut off and blows a hole in the part.
Computer is a laptop with 8 gb ram, and a 2.7 ghz processor, so I don't think it's a communication problem with the computer.
Since GCode is a one operation language the G01 line must end before reading the M9 line to turn off the welder.

The GCode is this simple:
M7
G01 x 3.73 F15
M9

Any ideas?

Thanks
Steve

Offline Tweakie.CNC

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Re: Mach 3 lag between stopping a move and M9
« Reply #1 on: June 07, 2017, 10:04:32 AM »
Hi Steve,

Try the M11 / M10 command set. These commands take effect at the instant of axis movement so your Gcode needs an extra line, such as…

M11
G01 X3.73 F15
M10
X3.74

In the ESS setup you can choose which Output pin (controlling your relay) is activated by the M11 / M10 commands.

Tweakie.
KEEP SAFE !
Re: Mach 3 lag between stopping a move and M9
« Reply #2 on: June 07, 2017, 11:31:17 AM »
Thanks much I will give that a try!
Appreciate the fast response!

Steve