main.cpp needs to be modified to reflect the number of units. It is a zero-based array, so for 7 possible unite, the value of 6 is used in both lines below: #if (NODE_SLOT_INDEX < 0) || (NODE_SLOT_INDEX > 6) #error "NODE_SLOT_INDEX must be 0..6" #endif INSERT SCREENSHOT HERE. To compile and load: time pio run -e flo -t upload --upload-port /dev/ttytFLO To monitor (replace with appropriate unit name) for Exercise 12: pio device monitor -d /usr/local/src/microreticulum/microReticulumTbeam/exercises/12_FiveTalk -e flo --port /dev/ttytFLO