use a older snapon plasma50 for DIY CNC

Hi all, I am wanting to use my older snapon plasma 50 with a DIY cnc i made, I am thinking linuxcnc is looking like the best way to control it and I am looking for any info about what I will need to be able to control the torch. From what I understand, I will need to be able to control the trigger, and also a signal of if the arc is on, with maybe a voltage divider to be able to read it to a pin on my controller?  I am on a tight budget, and I am wanting to do this a cheap as possible.  I would like to have torch height control if possible, and it looks like the mesa thc300 might do that, but does that only work with one of their control boards?  thanks for any help
 

You can use the THCAD2 with a parallel port based LinuxCNC system.
 

Ok, so I can use the THCAD2 to get arc voltage into controller, the reed relay and to get arc ok, and a relay to switch the trigger start. I was just about to give up on the idea of using my older shop plasma, only thing I think left to figure out is if my snapon plasma is a touch start, as non touch start seems to be important to use for a cnc?

I am trying to use remora and a BTT octopus that is already mounted to cnc, could I use the THCAD2 and input the FOUT- and FOUT+ as the "plasma up" and "plasma down", or as an encoder with ChA and ChB ?
remora code I think would apply for encoder?
{
"Thread": "Base",
"Type": "Encoder",
"Comment": "Encoder",
"PV": 2,
"ChA Pin": "8",
"ChB Pin": "7"
},

or remora code for plasma up and down?
"Type": "Digital Pin",
"Comment": "Plasma Up",
"Pin": "PG_16",
"Mode": "Input",
"Data Bit": 7
},
{
"Thread": "Servo",
"Type": "Digital Pin",
"Comment": "Plasma Down",
"Pin": "PB_7",
"Mode": "Input",
"Data Bit": 8
},

If the Remora can do a plain counter mode with its encoder inputs
It should be possible to make that work (it would be helpful if the
encoder also had a velocity pin)

what kinda of signal is it looking for linuxcnc side? dont know how well the velocity pin will work, but we can for sure count, it outputs the encoder as a float

If it can count a single signal then it can work.

If the low level encoder code does not provide a velocity pin,
you could calculate frequency using the ddt component,
but that will introduce noise proportional the servo thread jitter
relative to the servo thread period.

You could tradeoff bandwidth for noise by running the ddt thread
at a multiple of the servo thread period or low-pass filtering 
the result of the ddt.

The Mesa encoder velocity estimation works well for this as it
calculates velocity as counts/time_between_those_counts
The time between counts measured by timestamping
every count, so basically measures frequency based
on a crystal clock.

will the THCAD10 also work? I think I have a guy that has one I can buy for cheap, I ended up ordering a plamsa cutter that has a 1:1 voltage ratio, so can I use the THCAD10 with an external high voltage resistor?