Home to index - feeling dumb

I'm struggling with homing.  Not quite my first LCNC rodeo, but this is my first attempt at home-to-index and i can't seem to get either axis sorted out.

As it stands, the index pulse is found during homing, but it doesn't look like the DRO is updating with the correct HOME_OFFSET value... causing the axis to overtravel during the final move.

For Z axis (lathe)...here's what I want to happen:

1. Z moves positive to proxy (located close to hard EoT)
2. Z moves negative to index
3. DRO set to Z-2.25" when index triggered
4. Z moves positive 2.25" and stops
   1. i.e. short of proxy by 0.25"
5. DRO reads Z0 at final resting point
6. Max softlimit is Z0
7. Min softlimit is Z-12

Diagram of the Z-axis.

 

INI values
HOME = 0
HOME_OFFSET = -2.5
HOME_SEARCH_VEL = .1
HOME_LATCH_VEL = -.1
HOME_FINAL_VEL = .1
HOME_IGNORE_LIMITS = YES
HOME_SEQUENCE = 0
HOME_USE_INDEX = YES


PS:
Stumbled across this post:
forum.linuxcnc.org/49-basic-configuratio...ports-on-7i97#282558
that indicated there's been a bug for awhile... did the fix make it to 2.9?

The fix is in 2.9.0 onwards, but not in 2.8.

And I am not sure that it is enough of a bug to prevent it working altogether.

Do you have the joint.N.index-enable pins connected correctly?

@Andy,

The index-enable pins work.  I can see them trip in halshow when the readhead(s) move past them.

Connection in HAL:
As I mentioned, LCNC is moving to the final position once the index pulse is triggered.  Problem is that the DRO isn't getting reset to zero when index-enable triggers and so LCNC still 'thinks' that the proximity sensor is zero... not the encoder index.

Hardware wise, what should happen is that the
encoder count should be cleared (to 0) at index detection

I would verify this first

Now the post title is appropriate...

I had the home_offset too large and got confused which direction to calculate from.

Home to index is working now, minus the end-stop crashy part.

Repeats to +/-1 encoder count.  Really need this so I don't have to indicate my subspindle centerline every time I use the lathe.

Thanks gents.