Controlling a big stepper motor

If PUL+, ENA+ and DIR+ are connected to +5V and PUL-, ENA- and DIR- are wired to the output pins, that's LOW true, the input to the drive is active when the pin is pulled LOW, try changing your program logic to match. I'm not sure how ENA works, just leave it disconnected for now, set microsteps to 1 (200) and try.