Digi XLR PRO User Manual page 24

Getting started with the XLR PRO RF Module
DIO9/ON_SLEEP
An illuminated blue LED indicates that the DIO9/ON_SLEEP line is high.
5V line indicator
An illuminated red LED indicates that the 5 V line on the XLR PRO Module is powered. This light being
illuminated does not ensure the voltage on VDD_5V line is correct, it only indicates that a voltage is
present.
USB communication and loopback
Illuminated yellow LEDs indicate that UART, SPI, and GPIO lines are respectively enabled between the
USB port and the XLR PRO Module. An illuminated white LED for the UART echo indicates that
loopback in enabled.
XLR PRO Radio Frequency (RF) Module User Guide
Development Board for the XLR PRO RF Module
24