THCAD selection including ohmic sensing

PCW wrote:

Yes the 5i25 --> 7I76 config is wired the same as the 7I96 and 7I76E configs:
The encoder connector has 3 encoders with only 'A' channels so instead of
the standard 1 encoder with A,B,IDX you have 3 encoders with only 'A' pins

So I've flashed my 5i25 with the firmware you provided in this post and have verified that I do in fact have three "A" pins

I've got the THCAD-5 for ohmic sensing wired into what was encoder B+/-. When I start up linuxcnc it cannot find any other encoder pins. Here's a ss of what's available when viewed from my router config.

Following along with the documentation in the primer, it says hm2_7i76e.0.encoder.02.velocity. I'm trying to parallel this with a hm2_5i25.0.encoder.01(or 02).velocity . Obviously I'm missing something about how the 2 additional A channels are connected.

EDIT: Figured it out, forgot to enable the 2nd encoder in the machine hal file. "loadrt hm2_pci config=" num_encoders=2..."
Now it's running

PhillC54.
This is an interesting aproach, basically we are muxing the THCAD input, may be some processing power can be saved using only one encoder.
I re-draw your schematic just to make it more readable, I think this will require some changes to PlasmaC componet.
 

I don't think the contractor is required as the hypersensing circuit is impervious to high voltage.
Currently when the voltage exceeds 24 volts, the component is seeing an arc voltage and it never breaks now. The thcad always sees a bit past the full scale and the 390k resistor sets full scale to 23.5 volts anyway.

So what if you mux the  THCAD calibration instead? once it is > 24 volts, recalibrate it to be fullscale 200 or 300 volts?

Yes will need 2 factors one for the arc voltage and one for the Hypersensing, also the QtplasmaC need to change from THC to Hypersensing Mode.
 

The mode can be automatically selected based on voltage sensed. You know at startup its not cutting, start in hypersensing mode but if the voltage exceeds 24 volts, calibrate to THC range and stay there until it falls to say < 5 volts, go back to hypersensing mode.