Here is my proposed wiring schematic, which is a revised version of the wonderful plan shared by @kd2018 for his plasma control panel:
UPDATE 2022-12-26: Corrected the graphic to reflect that I am using THCAD-2 instead of THCAD-10.
UPDATE 2022-12-26 - B: Corrected the graphic again to reflect tweaks based on input from LinuxCNC forum answers, re. THCAD-2 grounding (no) & placement (on plasma machine), and re. 7i96S (switching “Torch On” from output 0 (-/+) to output 4 (-/+).
UPDATE 2023-01-23 - A: Corrected the graphic again to reflect that my control board is a 7i96S instead of a 7i96. This also included reflecting on the wiring diagram that the 5v power supply wires go into the back right corner — as the former location used on a non-S version is now (on the S version) for control of spindles.
Thanks again to @kd2018 & @vicious1 for their welcomed eyes on this.