Your missing a piece. The CAM (g-code generator) tells MACH when to turn on the plasma using a plasma specific POST. MACH figures out which physical output goes active for a specific "M" code. Normal operation is for the M03 to turn on an output (normally output1) and that is mapped to a pin on the BOB that will turn on a relay. The relay on the Sensor card you got with the THC would noramlly be used to turn on the torch but that can be remapped to any pin you have available. 2 axis? Mach uses the third axis as the THC control so how you gonna use that?
www.SoundLogicUS.com with contact info