OK I am using sheetcam to generate my Gcode.  Right now my pre processor is just about 6 lines.  What I want to know is how do I get the torch to touch off and set the height each time before turning on the torch.  I would like it to do this every time it turns off the torch and  starts to make a cut in another spot.  I have a THC that is standalone and once the torch is lighted it takes control of the Z-axis height and ignores input from mach4.  When the torch is off then mach4 can again take control of the Z-axis.  The THC is a Proma and has been a bit problematic for me to get it to give a steady control signal so after a while it builds up a lot of errors in distance and that is why I want to do a touch off to get a fresh start at the right height between each cut.  Does someone have a pre processor that would work with my setup that I could get a copy of? 

Hello
In my version of sheetcam there is a variable I can set to determine distance between probing. It is set within the post processor. I'm not at home now and can't give you the exact directions but I think it's under option, machine, post processor - pick your post and then click edit. You can set the distance between probes there in mine (I use the TNC3in1 height control). I am unsure about Proma posts but a lot of people use them so there must me a good post processor somewhere for them.
Steve

Thanks for the reply Steve.  I have only a few lines of gcode in my pre-processer.  I do not see any that I recognize as being Z-axis commands.  I need at least some example to learn from  but would love the whole shebang in one pile.  I do not even know what would tell sheetcam to touch off.  Here below is a cut and paste of the little fellow:

Mach4 plasma Post processor

Modal G-codes and coordinates
Comments enclosed with ( and )
M03/M05 turn the torch on/off
Intergrated Mach4 THC
No Z Moves
Incremental IJ

Hi
I read on the forth line from your code quoted "Integrated Mach4 THC". That is not the post processor you need as this is for the inbuilt torch height control that Mach 4 does. In the list of post processors that sheetcam has is there one that mentions Proma in it's title? If so select that and run it for a simple square you have drawn and post the gcode that it outputs and we can see more and advise you better. If there is no Proma post processor in sheetcam's list have a look for one - I suggest plasma spider is a good forum to join as you will get the help you need there and possibly a working post processor that will only need editing for the type of probing switch you use - floating head or ohmic.
Steve

Thanks for the reply Wallerawang.  I just looked through the files I have and do not see any mention of Proma.  I will try plasma spider as you have suggested.  Thanks again.

The standard Mach4 Plasma profile has a touch off routine as part of the M3 macro. Are you using this or your own profile and screenset? Do you have ohmic sense or floating head for initial height sense?

Thanks for the reply Swiftyj.  I am constructing a floating head right now.  I needed this information for when I get through.  I will look for the M3 macro and see what I can learn. 

Mr. SwiftyJ I have located that macro m3.mcc although I do not know what I will do with it.  I have also been looking at the THC screen in mach4.  Due to the fact that the Proma does not communicate with mach4 I had assumed that I could not use the THC screen.  Most likely a stupid mistake on my part.  I am guessing that when mach4 reads the gcode and sees that it is about to turn on the torch it will do a touch off if I have the touch off turned on in the THC screen?  Where do I configure mach4 to read the input from the switch on the torch touch off?  In fact if you understand this thing I would love to get a lesson in how it works from you or anyone willing to enlighten me.