Spindle Homing/Indexing w/external Index Pulse on non-1:1 spindle.

Ok guys/gals I’m getting oh so close to calling it good on my machine but I have one last issue. 

The spindle motor on this machine is a Servo motor that is geared up to go from 5k to 7.5k. So the encoder feedback is coming from the motor w/index. But, it has a hal sensor on the spindle shaft. I’d like to use that as an index. 

I have the hal sensor on one of the inputs on my 7i80 but it’s not the canned encoder index input as the motor has that taken. Also the sensor is 24v and the 7i33 doesn’t take accept 24v. 

Thanks 

Is the hal sensor a NPN or PNP (or push-pull) type?

It's sourcing, if it was sinking I'd be golden.

I see two possible solutions:

1. Two resistors as a voltage divider and thus no isolation
2. Optocoupling module for electrical isolation

Ok, I was wondering if there was a software option. But thank you.