Separate Spindle quadrature and index signals

So I have my VMC all running and cutting with the retrofit. All the motors are Fanuc. The Fanuc spindle has a quadrature encoder that only provides A and B signals (using a hall/VR sensor) and since it is belt connection to spindle (1:1 at that), the spindle has a separate sensor for an index hall sensor. How would I go about doing this with the Mesa cards. Can I separate the A and B signals out of the MESA encoder input and then use them with the NPN index signal to generate a "real" encoder signal?

Now to make it even more fun, is it possible to send this signal out as a A,B,Z signal to a VFD feedback card as well so the VFD can have a closed loop?

Cheers,
Omid

You can use a separate index input, it need not be synchronized with the encoder A/B signals
_if_ you are willing to tolerate a bit of uncertainty in index position.

The proximity sensor will probably be fairly stable but you will have a +- 1 count uncertainty because the
index edge will not be synchronized with the quadrature signals.

Whether you can connect this back to the VFD probably depends mostly on EMI and grounding issues
Something like a Ency part from Mesa may help here.

That's good to know. I already have the ENCY part as I had it all wired up hoping the Fanuc Spindle motor had the index as well. It has all the wiring, but the actual component is missing off of the encoder board. So would I just connect the index signal to the ENCY board as a Z or would I connect it separately to another input?

I would use the ENCY and jumper the Z input for TTL mode (and use a NPN PROX)

You could probably improve the noise immunity somewhat by adding a stronger pullup to
5V on the PROX output/ENCY index input (the ENCY has a 2K pullup but 220 Ohm or so would be better)

That's great! So I guess I should change the NPN PROX sensor to a 5V unit then since it is a 24V currently...

Its probably safer, a 24V PROX should be OK, especially if you have a 220 pullup to 5V
on the output (since its output is a switch to ground) but if you lose the ground connection
you will have a 24V source to the ENCY input though it wont supply much current.

That worked well. Seem like the inductive sensor actually works at 5V as well and was pretty much no noise. However I added the 220 pull-up for good measure. Thank you again!