5i25+7i76 Spindle and Encoder Setup

For the encoders, I've build a separate circuit for the spindle encoder to clean up the signals from the optical sensors. I have the A, B, and Index signals (0V to 12V) running through a comparator triggered at 50% maximum amplitude. After the comparator, the square wave signal runs through a voltage divider to bring it down to 5V. The signal from my board produces a clean square wave running between 0V and 5V. I've noticed that after I connect my board to the 7i76 input pins for A, B, and Index, the square wave signal no longer pulls down to 0V. Instead, the signal oscillates between 2.5V (roughly) and 5V. Is this typical or am I doing something incorrectly that's not allowing me see any spindle speed values on PNCconf?

Also, I still can't figure out why I can't get an output on the 7i76 for the Spindle speed controller. I've attached a photo of my 7i76 wiring connections. I might be doing something obviously wrong but I'm at a loss right now.

PCW, in your last post, you mentioned "2. hm2_5i25.0.7i76.0.0.spinena must be "true"". Does that mean I need to wire +6V to SPINENA or is that set to "true" programmatically?

hm2_5i25.0.7i76.0.0.spinena is a hal signal that must be true for the spindle analog output to be enabled
You can check this (and all the other signals in my list) with halmeter or "watch"

DO NOT connect external power to the SPINDLE ENA pins, these pins are connections to a
OPTO coupler output switch designed for enabling you spindle motor drive, that is SPINDLE ENA+ and SPINDLE ENA- are open circuit until linuxcnc is running and the hal pin hm2_5i25.0.7i76.0.0.spinena is asserted and then they are a
low resistance closed circuit. If you apply non current limited power directly to these outputs, you will damage the optocoupler

The likely reason that you do not have full swing on the 7I76 encoder inputs is because the inputs have 2K pullups
and your divider network is too high resistance to drive this to ground

Are the 7i76 encoder inputs safe to 12V? Is the conditioning even necessary?

Ok, Thanks for confirming. That's what I was assuming but I wanted to make sure. I'll play with the halmeter and see what hal signal I currently have for spindle enable.

I'll swap out and put in a lower resistance divider circuit to pull it closer to ground and see if I can get the Spindle Speed function to work.

PCW mentioned to me a few weeks ago that the A, B, and Index signals for the spindle must be 5V when wired into the 7i76.

Thanks for the help so far gents.

I finally have both the spindle speed encoders and analog output working.

Thanks for your help once again.