Hi Bruce from NZ,
Perhaps not what you want to hear but it is the best advice you could be given…
Junk the Bitsensor board, save yourself a lot of time and hassle, and buy a USA or EU manufactured motion controller which has a greater degree of support. That way you will be able to build a reliable machine capable of producing quality work.
Plasma cutters have a particular set of requirements (such as pierce delay, torch height control, etc., etc.) and these are just not fully supported by the Bitsensor.
Tweakie.