On the Original Prusa XL, communication with the peripheral boards (e.g. Dwarf board) is achieved using the MODBUS protocol. In MODBUS, there are two types of devices: the master and the slave, also known, respectively, as client and server. On Original Prusa XL firmware, the master is the XLBuddy, and each slave is called puppy.
Each puppy is assigned a unique address that is used by the XLBuddy. In case of an error in this procedure, the printer will show the message: "Address assignment error".
Error name: Puppy addr assign err
Error code: #17511
The error indicates most likely a configuration problem that might have stemmed from firmware.
Download the firmware and if necessary the bootloader compatible with your printer version, and transfer the files to your USB drive. Make sure to unmount the drive from your operating system before physically removing it.
Insert the USB drive back into the printer and reboot the printer using the reset button directly next to the knob to initiate the flashing procedure. In case the procedure does not start, reboot the printer again by pressing the same reset button, and while the printer is booting up, press once the rotating knob.