Mach3 and USB to cnc driver

[Neale]

I'm a little confused now as I understood that the UC100 was just for converting the PP to a USB configuration !

Indeed, that is part of the confusion. It's not obvious from the outside but the UC100 is not a USB to PP converter. Yes, it looks like it is, but it actually has a lot of added intelligence inside. To drive a CNC machine, you need something to read gcode, analyse it, work out where the axes need to move, and generate several series of precisely-timed pulses to drive each axis. Plus a user interface and the various housekeeping jobs like homing, managing limit switches, etc. Mach3 is OK for most of this, but can struggle with generating the precise timing that is needed for the various pulse trains to make a machine run smoothly at speed. Actually, the limiting factor is Windows, for various reasons, but we don't need to worry about that level of detail. The UC100 offloads the time-critical bits of the job - the pulse generation - and leaves Mach3 to do the bits it's better at. Again, this is an over-simplification but the general principle is correct. The UC100 is designed the way it is so that you can upgrade an existing PP system just by inserting the UC100, and installing and configuring its Mach3 plugin. If you have a spare usb port, it's as easy as that.

The UC100 is in current production with full support from its makers; I've no idea what's inside the fake versions but they are notoriously unreliable. You could think of the UC100 a bit like a grbl board - it does some of the trajectory planning ("where is the machine going?") and pulse generation, but needs something else to feed it gcode. My limited experience of grbl is that it works ok within its limitations but the various user interface options available are very limited; the UC100 works very well indeed and supports full Mach3 user interface functionality.

Additionally, because the UC100 offloads the time-critical bits, it allows Mach3 to run on versions of Windows which do not use the PP.