I used this code to use an external button to cycle start. I also have one for cycle stop and feed hold.
Code below:
-------------------------------Cycle Start-------------------------------
[mc.ISIG_INPUT16] = function (state) --If you are not using INPUT16 for Cycle Start change it.
InputCycleStart()
end,
---------------------------------------------------------------
-- The Input Signal for a Cycle Start Occurred.
---------------------------------------------------------------
function InputCycleStart()
CycleStart()
mc.mcCntlSetLastError(inst, "Cycle Start")
end