Index homing Heidenhain ls 403/exe602

Mine are old, so just basic LS403's with a single index. Sorry for that confusion.
Mark.

I think I can see a way to do this, as Andy explained I will take a look at this when I get a bit of free time.

Its a bit tricky because the first index detections ( used for latching the position ) will zero the position
so the latched count + encoder position must be used for feedback until the final homing to index
is done.

What I was thinking is that the detection of the desired position difference enables passing the index detection
to LinuxCNCs motion component.  

Truly grateful for all support here!

I checked my randomly-purchased liner scale (found at EMFCamp) and that is an LS 903 (no C) so is probably no help.

I figured it could be tested with a normal rotary encoder by setting the "home" detection 
index interval to the CPR of the encoder, so 2 index detection's with the proper delta
would arm LinuxCNC's index search.

I guess a fancier scheme would use it as an absolute scale ( generate the correct absolute
position after any  two index detection's  and a table lookup ) but I think that would need
a new homing routine rather than just a hal component.  

I am still looking into this, I did make a small change to the encoder driver to simplify
the index spacing detection. (I added the option to not zero the position on index detection)
This should simplify the distance coded index detection hal component, otherwise I would
have needed to undo the encoder position zeroing in the hal component, and that was pretty ugly.