How does PNCConfig and mesa encoder index-enable work?

I switched my parallel port lathe spindle quad encoder plus index over to a mesa 7i92/7i85. I configured with pncconfig and I can't get the encoder counts to reset. I see the correct A/B/Index signals on HalScope, but counts just keeps increasing (or decreasing if I reverse). Halmeter and scope show hm2_7i92.0.encoder.00.input-index going low when the index pulse comes around. I verified my encoder scale of 260/rev. I played with index-invert, index-mask, index-mask-invert, but I now believe the problem is with index-enable which never goes true???

Looking through the configuration, I see spindle-index-enable at the following lines:
net spindle-index-enable <=> pid.s.index-enable
net spindle-index-enable <=> hm2_7i92.0.encoder.00.index-enable
net spindle-index-enable <=> spindle.0.index-enable

How is spindle-index-enable supposed to get set true? Is this value supposed to come from a hardware signal or some GUI element? I don't have my spindle pwm connected so I tried commenting out the pid.s.index-enable with no success.

I also tried selecting the spindle with:
S100 $0
M3 $0

You actually don't need to unlink spindle.0.index-enable to test

(tri-state pins can be driven by any number of sources)

Thanks, I was looking at my problem incorrectly.

What wasn't working was the pypcp spindle speed display was jumping all over. I was only running spindle at 100RPM with 260 counts/rev and needed to reduce lowpass.spindle.gain.

So my mesa equipped lathe is now back to all the functionality I had with the PP. I played around with the closed loop stepper in pncconf and need to get the encoders mounted before I can add that functionality.

Thanks for all the help!

andypugh wrote:

Index-enable is set true only when required. This means that it is only ever set before a spindle-synchronised move.

If you want to test it, either try a G33 or G76, or open a terminal (with Linuxcnc running)

halcmd -kf
unlinkp spindle.0.index-enable
loadusr halmeter pin hm2_7i92.0.encoder.00.index-enable
loadusr halmeter pin hm2_7i92.0.encoder.00.counts
sets spindle-index-enable 1

Rotate the spindle by hand, and watch the halmeters
When happy, don't forget to re-connnect the pin, then exit

net spindle-index-enable spindle.0.index-enable
exit

I can do the above and I see the hm2_7i92.0.encoder.01.count increase from 0 to past 400 and the spindle-index-enable goes from true to false as the index occurs.
I then
net spindle-index-enable spindle.0.index-enable

But if I run a G33 or G33.1 I never see the hm2_7i92.0.encoder.01.index-enable go true.
What connection actually sets the index-enable true? Is there a connection with motion....

Solved: From the posting
forum.linuxcnc.org/20-g-code/34936-rigid-tapping-help?start=20
I set the encoder scale to negative. Now tapping cycle works.