I'm just getting into stepper motors and was looking at the best way to control one with a PLC. Do I need a stepper driver or would Openworlds Blackbox be able to communicate with a PLC?
you would need a driver (this is the simplest, a pulsed step pin and a direction pin) or the PLC has to speak Gcode to the blackbox via serial pins. read Grbl v1.1 Interface ยท gnea/grbl Wiki
