A definitive answer on closed loop encoder support

I am using Mach3, however I have no closed loop encoder support.

If I switch to LinuxCnc will i be able to set up closed loop with my longs stepper motor and drivers, along with the parallel port and quadrature encoder, or is there something more i need?

Thanks

The short answer: Yes, but...

There are a lot of questions that need to be answered. Such as the type of encoders being used, their scale/resolution, what step and count rates are to be expected, how is it all tied together at the machine...

As John mentioned, parallel ports are rather slow. Reading an encoder with a parallel port has the same speed limitations as stepping with it. Hence your encoder resolution would be limited to no better than your stepper resolution, and rates would probably need to be limited to within a safety margin.

Using a hardware encoder counter, would allow increasing the encoder resolution and rates to a much more useful level, as would adding hardware step generation. Luckily there is relatively inexpensive hardware that can do both. A Mesa 5i25, can generate step-rates and read encoders at Mhz speeds. However I would recommend adding one of Mesa's daughter cards to add differential signalling and signal conditioning. The 7i85S, that can read 4 differential encoders (with index) and 4 differential step/dir signals.