Wiring for stand alone usage with ATX power supply is missing. For ATX power supply (controlled with RUMBA)
Set the power jumper in "stand alone" position Connect GND from your ATX power supply to USB header Pin1 (where the arrow is) Connect 5 VSB from your ATX power supply (+5 VDC Standby Voltage) to USB header Pin4 Connect GND and PS ON (Power Supply On) from your ATX power supply to PS ON header, polarity doesn't matter
You'r now able to switch your power supply on and off via gcode or smart controler. With +5 VDC Standby Voltage RUMBA is always powered on even if the power supply is turned of via software.
Would it be possible to add a section on how to set things up for the first time?
I'm not sure if this standard across all suppliers of the board, but when I first turned mine on it started running the motors, and this doesn't give you enough time to flash firmware before it runs carriages off the end of the axes. In order to stop this, you can swap the jumper from the standalone power to the USB power.
In addition, it might be useful to list the modifications you need to make to pins.h in Marlin in order to get dual Z drivers working. You need to add entries for the Z2 pins, AND you need to define Z_DUAL_STEPPER_DRIVERS in configuration_adv.h, which isn't immediately obvious. Likewise for dual Y drivers if appropriate, though you'd also need to disable some logic on configuration_adv.h which checks that you don't have dual Z and dual Y drivers enable, because there aren't usually enough stepper drivers.
I'm just wondering if it is possible to link 2 RUMBAs together for 12 stepper drivers in total?
Or alternatively make an expansion that has that many steppers.