| FPort | LoRaWAN payload | + ------ + --------------------------- + ------------------------- + | RuleID | W | FCN = b'1 | RCS | Payload | Opt padding | + ------ + ----- + --------- + ------- + ----------- + ----------- + | 8 bits | 1 bit | 1 bit | 32 bits | 6 to X bits | 0 to 7 bits |