PLASMA CNC Material detection system

Hi everyone, i am a new comer to LINUXCNC and currently using MACH3 for my home brew CNC PLASMA cutter. I want to switch to LINUXCNC ASAP, but there are some obstacles due to my hardware configuration i have,

I use a relay system to detect material and for that i need to trigger some output pins during torch touch down and before the torch fires up, in MACH3, it`s a simple VB script but i wonder how can i achieve it using LINUXCNC.

here is an example of that code

Sleep(1000)
ActivateSignal(Output2) 'Turn ON probe sensing


Cfr = GetDro(18)
Code"G31 Z200 F500"
While Ismoving()
Wend

DeActivateSignal(Output2) 'Turn OFF probe sensing

Sleep(200)

Code"G92 Z0.00"
While Ismoving()
Wend

Code"G0 Z -3.00 F700" 'Pierce Height
While Ismoving()
Wend

Sleep(1000)





DoSpinCW()

Code"G4 P 1.1" ' Time delay

While Ismoving()
Wend


SetDro(18,Cfr)
While Ismoving()
Wend

A quick response to the problem would be much helpful.

I'll talk about the old school way first. Linuxcnc is a bit more sophisticated than Mach when it comes to probing. There is no need to script anything as it can be done in gcode

BigJohnT has a n example touchoff procedure

See gnipsel.com/shop/plasma/plasma.xhtml

This can be expanded somewhat to probe down fast with G38.2 than probe up more slowly with G38.5
See: linuxcnc.org/docs/2.8/html/gcode/g-code.html#gcode:g38

You can turn your relays on and off from gcode using M62-M65
linuxcnc.org/docs/2.8/html/gcode/m-code.html#mcode:m62-m65

But the better way would be to implement Phill's amazing Plasmac config in the docs for V 2.8 and V 2.9
See linuxcnc.org/docs/2.8/html/plasma/plasmac-user-guide.html

and don't forget to review the plasma primer
linuxcnc.org/docs/2.8/html/plasma/plasma-cnc-primer.html

So if you go down the Plasmac path you would reconfigure your relays as per the circuit diagram in the primer as follows:

1. 1 x double pole or 2 x single pole relays to keep the sensing circuit disconnected when not in use (triggered by an output)
2. 1 x single pole relay which is activated on material contact. It is used to trigger an input which is your probe signal.

Hi Tommy
Where is the best place to go look to get information to get started on PlasmaC?

Thanks Phil
That is one hugely comprehensive user guide. Absolutely awesome work.