How to configure extension board steppers on RADDS

Hi. I am building a large format printer with 3 stepper motors controlling the bed height (Z axis) and 2 extruders.
I am using RADDS with the extension board.
I need to know which two stepper drivers I should attach the additional two Z stepper motors to (physically which pins) and how to setup the firmware so the 3 motors are controlled correctly. In the schematic, there are a variety of pin numbers for the extension board. Does one of those numbers correspond to the pins definitions? Is there already a label in the firmware for the two extra drivers? I guess I'm trying to determine which set of drivers pins is which...

Some help with this would be most appreciated!
Thank you,


  • I think the motors on extension board are already configured as ext3 and ext4. Only thing I'm unsure is if this is for 2 or 3 stepper driver extension board. But I think it is for 2 extruder extension board.
  • What determines which is which? Is it one of the pin numbers assigned to drive a given stepper controller? Is the number the same as the ones in the pins.h in the firmware?
  • If you use config tool just select the socket. It will us ethe pin description from pins.h in 402 section whcih is radds. Ext0-2 are on board so 3-5 are for extension boards.
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