The plasmac component does not use Arc OK for spotting.
It was removed a long time back as many users were finding that by the time an ArcOK was received then they were getting too large a crater.
It is time based to a resolution of one thread cycle (in most cases 1mS) plus a voltage threshold for timer start may optionally be used.
Thanks for the update Phill. My Linuxcnc user guide must be way out of date LOL.
So could you clarify, if I set the voltage threshold at zero, would timing start from when the Torch On signal is given ?
I don't think its wise to start the spotting timer at the torch on signal. The reason why spotting looks for a voltage increase is that there are significant variations in relay hysteresis/delay times between different builds. Eg I might use the 7i76e spindle enable on board relay to fire the torch and you might use an external relay with 120 ms trigger time. I might get away with a 220 ms spot delay but you might need 340ms to get the same delay. When we first tested this and Phil was coding the idea, we just went with a delay from the torch turn on but we found huge differences in results so waiting for a voltage to be seen, removed some of the variations we observed.
You really need to do some work in halscope to understand the parameters but I would expect say a 10 volt threshold would be achieved within the space of a servo thread cycle from torch turn on. The threshold just needs to be high enough so the normal voltage fluctuations don't cause spurious triggers.
