Hi,
Mike is right, there are some specific functions that are done by the motion controller. Many, like homing and probing, are now so commonplace that they
could be regarded as standard and to my knowledge all of the devices by the manufacturers I've listed to do it.
The functions where there is significant variance in the different device offerings is THC, backlash compensation and single point lathe threading.
If you require any or all of those functions you will have to do some careful research, its often not plain what each device is capable of.
One of the more expensive units, the Hicon of Vital Systems is capable of all three, my guess is the extra budget that a higher sales price makes possible
has seen Vital Systems lead the pack when it comes to implementing sophisticated controller level functions.
Warp9's ESS has code to enact all three but as yet none of the functions (backlash compensation, THC or lathe threading) is bug free yet and they have been working
on them for a while. You may get very frustrated if you required THC for instance and bought an ESS in anticipation that THC is just round the corner.
CNCDirve's UC100 and UC300 have a good reputation in Mach3 circles but the UC100 has had a Mach4 plugin for less than a year and the UC300 for only
a few months. It seems unlikely that they will have implemented these functions yet. All the basic stuff they do well. You should email and get genuine clarity
about special functions if such a function is required in your machine.
Craig