steppers with encoders

Hello Everyone!

I'm new here and i don know if i'm putting my question in the right place!
I've been testing emc for some time, i made my own optoisolated parallel port breakout board and the stepper amps.
Now, iḿ working on the machine structure, wich is a 3 axis mill.
Everything is going great with linux and with the steppers but i would like to give one step further.
I want some kind of encoding system for my steppers, but only with parallel ports(one more) for the inputs.
I know that are many options available, like mesa cards, but i guess they are only for servos...
Can anyone give me an idea? And is it possible to do with stepper motors, directly on emc?

Thanks in advance!

If you want to try this I would recomend a Mesa 5i25 with a 7i85S combo. I'm not sure how it would shake out in the end, but that would be the best hardware to start with that I can think of. The drives may matter more, and don't expect true servo performance from this either.

This would get you very fast and smooth hardware step generation and encoder feedback, so you can try very fine micro-stepping.

I'm still not convinced it is going to work all that great.

You can do this but you cannot typically cannot improve performance over
plain step motor drives much if at all.

There are exceptions, for example systems with accurate linear scales can use the
scale as the position reference, effectively using the stepmotor/step drive as a velocity
mode servo drive and gaining better accuracy.

Some advantages of a step motor drive system with encoder feedback via linuxcnc:

Fast stall detection (stall prevention _might_ be possible but is complex and requires a very fast thread).
Accurate homing to encoder index.
No need to rehome after a stall/fault.