Robertspark wrote:Ooh.... uc300eth.... I see a direct thc interface coming .... well direct with the 50:1 etc voltage divider..... (I have a pmx45, so part of the hard work is done via the interface)
Also fancy having a go at changing the current pot for a digital pot so current can be set and adjusted (tweaked) relative to feedrate... or using an il300 as a linear optocoupler via one of the analogue outputs, may need a faster loop than plugin at 25hz... the options look good
Rob
The analog input currently can't be used as the THC control signal unfortunately.
I also think (but will have to check) that the analog signal is probably filtered with a too high time constant (for good noise immunity) on the -5LPT motherboard for this to work,
I mean probably it could not work, because of the limitation of the board and also the analog signal is not sampled at high speed,
the analog signal works for Feedrate override, Spindle speed override and jog override and can be attached to # variables,
and these does not need real fast processing. I think the processing is about 20Hz currently.
The loop in the plugin is 25Hz, because for most things that is enough and you know the higher the loop speed the more CPU time the PC will need,
so we set that to a 25Hz frequency, but ofcourse you can create your own Timers or your own Threads and run your own loops which can be any fast you building it in the plugin.
But this will not make the analog sampling faster and also the analog low-pass filter time constant I mentioned is still there and can't be resolved with faster sampling.
Basicly the board and code was not designed to control plasma based on the analog input signal. It is a good idea, but we did not think about it when designing the motherboard.
The THC control is currently built around digital inputs only from external THC controller with THC up, down and ARCOK signals.