7i76 Spindle Encoder Index Signal

Found another quad encoder to try for my lathe project but this one has an index signal. I'm not sure if I can use this unless I can get a 1:1 ratio on the spindle to encoder but it's an option if I can get it to fit

Checked the encoder on a scope and it shows a nice index signal so I know the encoder is working

Is there any way to test that it's functioning correctly in linuxcnc?
Thanks
M

yes, you halmeter and "sets" the signal thats linked to index enable true
Then you rotate the encoder, the signal should stay true until you hit index.

Under signals I see
Spindle-index-enable but it shows FALSE with no change if I slowly rotate the encoder
Is possible the index is so small it doesn't pick it up even though I'm going pretty slow? (I really should try to figure out how to use halscope)
M

You need to "sets" the signal true:

halcmd sets spindle-index-enable true

Ahhh OK, typed that into the terminal window and it switched on the Hal Meter to TRUE
turned the encoder and at some point it flips to false and stays there even if I continue to rotate, more of a state change but looks like this is good

If I can get it to fit with a 1:1 ratio I can use this encoder (2048 count but ball bearing shaft)
If I can't run a 1:1 ratio I can use the existing 1 notch index disc and this encoder
if it doesn't fit I'll have to go for the smaller encoder with no index and use the existing index disc
One way or another I think I've got the spindle feedback covered.

Huge progress with all the help here
Thanks again
M

Yes, its a state change

What happens in normal use is that when LinuxCNC needs to search for index
(say when starting a threading cycle) it sets its index enable output and waits until
the encoder logic clears the signal. When this happens,
1. LinuxCNCs motion component knows index has been detected, and
2. The position count is cleared when index occurred so motion knows that
the current position is relative to index.

Interesting
Does it just set it (relative) once per motion or does it keep looking at it compared to the feed rate?
I guess what I'm wondering is on a really long thread it makes sure the start is in the correct orientation point but after that is it relying on the rpm/feed to be constant or if the rpm fluctuated (lets say slows down for some reason) will it make feed adjustments to keep everything in the proper relationship?
(not that I do much long threads or anything just curious how it works on the inside)

Again, many thanks for the guidance
M

AFAIK LinuxCNC only synchronizes on index at the start of a threading or
tapping pass, _but_ the whole Z axis motion is "geared" to the spindle
encoder position at this point so will track any spindle speed variations

Yeah I figure I can run some form of encoder off any of the gear train but the index needs to be at the same speed as the end spindle.
I'm looking at gears in the background right now but I'm thinking just to keep going I'll make a bushing to fit into the rear of the spindle bore and put the encoder (with index) I have into that with some sort of bracket to hold the case still.
Later on I can rig up something permanent that allows through bore (I end up with shafting out the back of the spindle more often than you'd think)

It looks like a pair of 30xl037 pulleys might be made to work if I bore out the center and make a different mount collar on the one (hmmm sounds like I'll need a lathe.....)
M